diff --git a/backtracking/all_combinations.py b/backtracking/all_combinations.py
index 60e9579f2..854dc5198 100644
--- a/backtracking/all_combinations.py
+++ b/backtracking/all_combinations.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 """
         In this problem, we want to determine all possible combinations of k
         numbers out of 1 ... n. We use backtracking to solve this problem.
diff --git a/ciphers/brute_force_caesar_cipher.py b/ciphers/brute_force_caesar_cipher.py
index 2586803ba..5f11cb848 100644
--- a/ciphers/brute_force_caesar_cipher.py
+++ b/ciphers/brute_force_caesar_cipher.py
@@ -40,7 +40,7 @@ def decrypt(message):
                 translated = translated + LETTERS[num]
             else:
                 translated = translated + symbol
-        print("Decryption using Key #%s: %s" % (key, translated))
+        print(f"Decryption using Key #{key}: {translated}")
 
 
 def main():
diff --git a/ciphers/hill_cipher.py b/ciphers/hill_cipher.py
index e01b6a3f4..05f716f85 100644
--- a/ciphers/hill_cipher.py
+++ b/ciphers/hill_cipher.py
@@ -78,7 +78,7 @@ class HillCipher:
         req_l = len(self.key_string)
         if gcd(det, len(self.key_string)) != 1:
             raise ValueError(
-                "discriminant modular {0} of encryption key({1}) is not co prime w.r.t {2}.\nTry another key.".format(
+                "discriminant modular {} of encryption key({}) is not co prime w.r.t {}.\nTry another key.".format(
                     req_l, det, req_l
                 )
             )
diff --git a/ciphers/rsa_cipher.py b/ciphers/rsa_cipher.py
index a9b2dcc55..da3778ae9 100644
--- a/ciphers/rsa_cipher.py
+++ b/ciphers/rsa_cipher.py
@@ -101,7 +101,7 @@ def encryptAndWriteToFile(
     for i in range(len(encryptedBlocks)):
         encryptedBlocks[i] = str(encryptedBlocks[i])
     encryptedContent = ",".join(encryptedBlocks)
-    encryptedContent = "%s_%s_%s" % (len(message), blockSize, encryptedContent)
+    encryptedContent = "{}_{}_{}".format(len(message), blockSize, encryptedContent)
     with open(messageFilename, "w") as fo:
         fo.write(encryptedContent)
     return encryptedContent
diff --git a/ciphers/rsa_key_generator.py b/ciphers/rsa_key_generator.py
index ce7c1f3dd..729d31c08 100644
--- a/ciphers/rsa_key_generator.py
+++ b/ciphers/rsa_key_generator.py
@@ -43,11 +43,11 @@ def makeKeyFiles(name, keySize):
     publicKey, privateKey = generateKey(keySize)
     print("\nWriting public key to file %s_pubkey.txt..." % name)
     with open("%s_pubkey.txt" % name, "w") as fo:
-        fo.write("%s,%s,%s" % (keySize, publicKey[0], publicKey[1]))
+        fo.write("{},{},{}".format(keySize, publicKey[0], publicKey[1]))
 
     print("Writing private key to file %s_privkey.txt..." % name)
     with open("%s_privkey.txt" % name, "w") as fo:
-        fo.write("%s,%s,%s" % (keySize, privateKey[0], privateKey[1]))
+        fo.write("{},{},{}".format(keySize, privateKey[0], privateKey[1]))
 
 
 if __name__ == "__main__":
diff --git a/ciphers/shuffled_shift_cipher.py b/ciphers/shuffled_shift_cipher.py
index bbefe3305..be5c6caf8 100644
--- a/ciphers/shuffled_shift_cipher.py
+++ b/ciphers/shuffled_shift_cipher.py
@@ -2,7 +2,7 @@ import random
 import string
 
 
-class ShuffledShiftCipher(object):
+class ShuffledShiftCipher:
     """
     This algorithm uses the Caesar Cipher algorithm but removes the option to
     use brute force to decrypt the message.
diff --git a/ciphers/simple_substitution_cipher.py b/ciphers/simple_substitution_cipher.py
index 12511cc39..7da18482d 100644
--- a/ciphers/simple_substitution_cipher.py
+++ b/ciphers/simple_substitution_cipher.py
@@ -17,7 +17,7 @@ def main():
         mode = "decrypt"
         translated = decryptMessage(key, message)
 
-    print("\n%sion: \n%s" % (mode.title(), translated))
+    print("\n{}ion: \n{}".format(mode.title(), translated))
 
 
 def checkValidKey(key):
diff --git a/ciphers/xor_cipher.py b/ciphers/xor_cipher.py
index 17e45413a..58b535267 100644
--- a/ciphers/xor_cipher.py
+++ b/ciphers/xor_cipher.py
@@ -18,7 +18,7 @@
 """
 
 
-class XORCipher(object):
+class XORCipher:
     def __init__(self, key=0):
         """
                         simple constructor that receives a key or uses
diff --git a/compression/burrows_wheeler.py b/compression/burrows_wheeler.py
index 50ee62aa0..1c7939b39 100644
--- a/compression/burrows_wheeler.py
+++ b/compression/burrows_wheeler.py
@@ -135,16 +135,14 @@ def reverse_bwt(bwt_string: str, idx_original_string: int) -> str:
         idx_original_string = int(idx_original_string)
     except ValueError:
         raise TypeError(
-            (
-                "The parameter idx_original_string type must be int or passive"
-                " of cast to int."
-            )
+            "The parameter idx_original_string type must be int or passive"
+            " of cast to int."
         )
     if idx_original_string < 0:
         raise ValueError("The parameter idx_original_string must not be lower than 0.")
     if idx_original_string >= len(bwt_string):
         raise ValueError(
-            ("The parameter idx_original_string must be lower than" " len(bwt_string).")
+            "The parameter idx_original_string must be lower than" " len(bwt_string)."
         )
 
     ordered_rotations = [""] * len(bwt_string)
diff --git a/data_structures/binary_tree/avl_tree.py b/data_structures/binary_tree/avl_tree.py
index 31d12c811..2df747c10 100644
--- a/data_structures/binary_tree/avl_tree.py
+++ b/data_structures/binary_tree/avl_tree.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 An auto-balanced binary tree!
 """
diff --git a/data_structures/binary_tree/red_black_tree.py b/data_structures/binary_tree/red_black_tree.py
index 908f13cd5..088476650 100644
--- a/data_structures/binary_tree/red_black_tree.py
+++ b/data_structures/binary_tree/red_black_tree.py
@@ -467,7 +467,7 @@ class RedBlackTree:
         from pprint import pformat
 
         if self.left is None and self.right is None:
-            return "'%s %s'" % (self.label, (self.color and "red") or "blk")
+            return "'{} {}'".format(self.label, (self.color and "red") or "blk")
         return pformat(
             {
                 "%s %s"
diff --git a/data_structures/binary_tree/treap.py b/data_structures/binary_tree/treap.py
index 6bc2403f7..d2e3fb88e 100644
--- a/data_structures/binary_tree/treap.py
+++ b/data_structures/binary_tree/treap.py
@@ -2,7 +2,7 @@ from random import random
 from typing import Tuple
 
 
-class Node(object):
+class Node:
     """
     Treap's node
     Treap is a binary tree by value and heap by priority
@@ -18,11 +18,10 @@ class Node(object):
         from pprint import pformat
 
         if self.left is None and self.right is None:
-            return "'%s: %.5s'" % (self.value, self.prior)
+            return f"'{self.value}: {self.prior:.5}'"
         else:
             return pformat(
-                {"%s: %.5s" % (self.value, self.prior): (self.left, self.right)},
-                indent=1,
+                {f"{self.value}: {self.prior:.5}": (self.left, self.right)}, indent=1,
             )
 
     def __str__(self):
diff --git a/data_structures/data_structures/heap/heap_generic.py b/data_structures/data_structures/heap/heap_generic.py
index fc17c1b12..8993d5013 100644
--- a/data_structures/data_structures/heap/heap_generic.py
+++ b/data_structures/data_structures/heap/heap_generic.py
@@ -1,4 +1,4 @@
-class Heap(object):
+class Heap:
     """A generic Heap class, can be used as min or max by passing the key function accordingly.
     """
 
diff --git a/data_structures/hashing/hash_table.py b/data_structures/hashing/hash_table.py
index ab473dc52..69eaa65d8 100644
--- a/data_structures/hashing/hash_table.py
+++ b/data_structures/hashing/hash_table.py
@@ -28,7 +28,7 @@ class HashTable:
 
     def _step_by_step(self, step_ord):
 
-        print("step {0}".format(step_ord))
+        print(f"step {step_ord}")
         print([i for i in range(len(self.values))])
         print(self.values)
 
diff --git a/data_structures/stacks/stack.py b/data_structures/stacks/stack.py
index 9f5b27971..53a40a7b7 100644
--- a/data_structures/stacks/stack.py
+++ b/data_structures/stacks/stack.py
@@ -1,7 +1,7 @@
 __author__ = "Omkar Pathak"
 
 
-class Stack(object):
+class Stack:
     """ A stack is an abstract data type that serves as a collection of
     elements with two principal operations: push() and pop(). push() adds an
     element to the top of the stack, and pop() removes an element from the top
diff --git a/digital_image_processing/histogram_equalization/histogram_stretch.py b/digital_image_processing/histogram_equalization/histogram_stretch.py
index b6557d6ef..d4a6c0841 100644
--- a/digital_image_processing/histogram_equalization/histogram_stretch.py
+++ b/digital_image_processing/histogram_equalization/histogram_stretch.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Created on Fri Sep 28 15:22:29 2018
 
diff --git a/digital_image_processing/index_calculation.py b/digital_image_processing/index_calculation.py
index fc5b16965..0786314e1 100644
--- a/digital_image_processing/index_calculation.py
+++ b/digital_image_processing/index_calculation.py
@@ -389,10 +389,7 @@ class IndexCalculation:
             :return: index
         """
         return np.arctan(
-            (
-                ((2 * self.red - self.green - self.blue) / 30.5)
-                * (self.green - self.blue)
-            )
+            ((2 * self.red - self.green - self.blue) / 30.5) * (self.green - self.blue)
         )
 
     def IVI(self, a=None, b=None):
diff --git a/dynamic_programming/fast_fibonacci.py b/dynamic_programming/fast_fibonacci.py
index 47248078b..77094a403 100644
--- a/dynamic_programming/fast_fibonacci.py
+++ b/dynamic_programming/fast_fibonacci.py
@@ -1,5 +1,4 @@
 #!/usr/bin/python
-# encoding=utf8
 
 """
 This program calculates the nth Fibonacci number in O(log(n)).
diff --git a/dynamic_programming/k_means_clustering_tensorflow.py b/dynamic_programming/k_means_clustering_tensorflow.py
index 6b1eb628e..4fbcedeaa 100644
--- a/dynamic_programming/k_means_clustering_tensorflow.py
+++ b/dynamic_programming/k_means_clustering_tensorflow.py
@@ -40,7 +40,7 @@ def TFKMeansCluster(vectors, noofclusters):
         ##First lets ensure we have a Variable vector for each centroid,
         ##initialized to one of the vectors from the available data points
         centroids = [
-            tf.Variable((vectors[vector_indices[i]])) for i in range(noofclusters)
+            tf.Variable(vectors[vector_indices[i]]) for i in range(noofclusters)
         ]
         ##These nodes will assign the centroid Variables the appropriate
         ##values
diff --git a/dynamic_programming/matrix_chain_order.py b/dynamic_programming/matrix_chain_order.py
index f88a9be8a..9411bc704 100644
--- a/dynamic_programming/matrix_chain_order.py
+++ b/dynamic_programming/matrix_chain_order.py
@@ -46,7 +46,7 @@ def main():
     # 30*35 35*15 15*5 5*10 10*20 20*25
     Matrix, OptimalSolution = MatrixChainOrder(array)
 
-    print("No. of Operation required: " + str((Matrix[1][n - 1])))
+    print("No. of Operation required: " + str(Matrix[1][n - 1]))
     PrintOptimalSolution(OptimalSolution, 1, n - 1)
 
 
diff --git a/graphs/basic_graphs.py b/graphs/basic_graphs.py
index 161bc0c09..070af5f55 100644
--- a/graphs/basic_graphs.py
+++ b/graphs/basic_graphs.py
@@ -48,7 +48,7 @@ if __name__ == "__main__":
 
 
 def dfs(G, s):
-    vis, S = set([s]), [s]
+    vis, S = {s}, [s]
     print(s)
     while S:
         flag = 0
@@ -76,7 +76,7 @@ from collections import deque
 
 
 def bfs(G, s):
-    vis, Q = set([s]), deque([s])
+    vis, Q = {s}, deque([s])
     print(s)
     while Q:
         u = Q.popleft()
@@ -255,7 +255,7 @@ def krusk(E_and_n):
     # Sort edges on the basis of distance
     (E, n) = E_and_n
     E.sort(reverse=True, key=lambda x: x[2])
-    s = [set([i]) for i in range(1, n + 1)]
+    s = [{i} for i in range(1, n + 1)]
     while True:
         if len(s) == 1:
             break
diff --git a/graphs/breadth_first_search.py b/graphs/breadth_first_search.py
index 8516e60a5..faa166150 100644
--- a/graphs/breadth_first_search.py
+++ b/graphs/breadth_first_search.py
@@ -1,5 +1,4 @@
 #!/usr/bin/python
-# encoding=utf8
 
 """ Author: OMKAR PATHAK """
 
diff --git a/graphs/depth_first_search.py b/graphs/depth_first_search.py
index 5347c2fbc..2fe9dd157 100644
--- a/graphs/depth_first_search.py
+++ b/graphs/depth_first_search.py
@@ -1,5 +1,4 @@
 #!/usr/bin/python
-# encoding=utf8
 
 """ Author: OMKAR PATHAK """
 
diff --git a/graphs/edmonds_karp_multiple_source_and_sink.py b/graphs/edmonds_karp_multiple_source_and_sink.py
index eb6ec739b..0f359ff1a 100644
--- a/graphs/edmonds_karp_multiple_source_and_sink.py
+++ b/graphs/edmonds_karp_multiple_source_and_sink.py
@@ -57,7 +57,7 @@ class FlowNetwork:
         self.maximumFlowAlgorithm = Algorithm(self)
 
 
-class FlowNetworkAlgorithmExecutor(object):
+class FlowNetworkAlgorithmExecutor:
     def __init__(self, flowNetwork):
         self.flowNetwork = flowNetwork
         self.verticesCount = flowNetwork.verticesCount
@@ -80,7 +80,7 @@ class FlowNetworkAlgorithmExecutor(object):
 
 class MaximumFlowAlgorithmExecutor(FlowNetworkAlgorithmExecutor):
     def __init__(self, flowNetwork):
-        super(MaximumFlowAlgorithmExecutor, self).__init__(flowNetwork)
+        super().__init__(flowNetwork)
         # use this to save your result
         self.maximumFlow = -1
 
@@ -93,7 +93,7 @@ class MaximumFlowAlgorithmExecutor(FlowNetworkAlgorithmExecutor):
 
 class PushRelabelExecutor(MaximumFlowAlgorithmExecutor):
     def __init__(self, flowNetwork):
-        super(PushRelabelExecutor, self).__init__(flowNetwork)
+        super().__init__(flowNetwork)
 
         self.preflow = [[0] * self.verticesCount for i in range(self.verticesCount)]
 
diff --git a/graphs/graph_list.py b/graphs/graph_list.py
index 4f0cbf15c..a20940ab1 100644
--- a/graphs/graph_list.py
+++ b/graphs/graph_list.py
@@ -1,12 +1,11 @@
 #!/usr/bin/python
-# encoding=utf8
 
 # Author: OMKAR PATHAK
 
 # We can use Python's dictionary for constructing the graph.
 
 
-class AdjacencyList(object):
+class AdjacencyList:
     def __init__(self):
         self.List = {}
 
diff --git a/hashes/hamming_code.py b/hashes/hamming_code.py
index 155c1b10a..3e0424490 100644
--- a/hashes/hamming_code.py
+++ b/hashes/hamming_code.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Author: João Gustavo A. Amorim & Gabriel Kunz
 # Author email: joaogustavoamorim@gmail.com and gabriel-kunz@uergs.edu.br
 # Coding date:  apr 2019
@@ -100,7 +99,7 @@ def emitterConverter(sizePar, data):
         # Performs a template of bit positions - who should be given,
         # and who should be parity
         if qtdBP < sizePar:
-            if ((np.log(x) / np.log(2))).is_integer():
+            if (np.log(x) / np.log(2)).is_integer():
                 dataOutGab.append("P")
                 qtdBP = qtdBP + 1
             else:
@@ -170,7 +169,7 @@ def receptorConverter(sizePar, data):
         # Performs a template of bit positions - who should be given,
         #  and who should be parity
         if qtdBP < sizePar:
-            if ((np.log(x) / np.log(2))).is_integer():
+            if (np.log(x) / np.log(2)).is_integer():
                 dataOutGab.append("P")
                 qtdBP = qtdBP + 1
             else:
@@ -204,7 +203,7 @@ def receptorConverter(sizePar, data):
         # Performs a template position of bits - who should be given,
         # and who should be parity
         if qtdBP < sizePar:
-            if ((np.log(x) / np.log(2))).is_integer():
+            if (np.log(x) / np.log(2)).is_integer():
                 dataOutGab.append("P")
                 qtdBP = qtdBP + 1
             else:
diff --git a/linear_algebra/src/lib.py b/linear_algebra/src/lib.py
index 15d176cc6..f4628f1d9 100644
--- a/linear_algebra/src/lib.py
+++ b/linear_algebra/src/lib.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Created on Mon Feb 26 14:29:11 2018
 
@@ -25,7 +24,7 @@ import math
 import random
 
 
-class Vector(object):
+class Vector:
     """
         This class represents a vector of arbitrary size.
         You need to give the vector components. 
@@ -205,7 +204,7 @@ def randomVector(N, a, b):
     return Vector(ans)
 
 
-class Matrix(object):
+class Matrix:
     """
     class: Matrix
     This class represents a arbitrary matrix.
diff --git a/linear_algebra/src/test_linear_algebra.py b/linear_algebra/src/test_linear_algebra.py
index f8e7db7de..5e28910af 100644
--- a/linear_algebra/src/test_linear_algebra.py
+++ b/linear_algebra/src/test_linear_algebra.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Created on Mon Feb 26 15:40:07 2018
 
diff --git a/machine_learning/k_means_clust.py b/machine_learning/k_means_clust.py
index 4c643226b..7a4f69eb7 100644
--- a/machine_learning/k_means_clust.py
+++ b/machine_learning/k_means_clust.py
@@ -126,7 +126,7 @@ def plot_heterogeneity(heterogeneity, k):
     plt.plot(heterogeneity, linewidth=4)
     plt.xlabel("# Iterations")
     plt.ylabel("Heterogeneity")
-    plt.title("Heterogeneity of clustering over time, K={0:d}".format(k))
+    plt.title(f"Heterogeneity of clustering over time, K={k:d}")
     plt.rcParams.update({"font.size": 16})
     plt.show()
 
@@ -164,7 +164,7 @@ def kmeans(
             num_changed = np.sum(prev_cluster_assignment != cluster_assignment)
             if verbose:
                 print(
-                    "    {0:5d} elements changed their cluster assignment.".format(
+                    "    {:5d} elements changed their cluster assignment.".format(
                         num_changed
                     )
                 )
diff --git a/machine_learning/logistic_regression.py b/machine_learning/logistic_regression.py
index f23d400ce..f5edfb9c5 100644
--- a/machine_learning/logistic_regression.py
+++ b/machine_learning/logistic_regression.py
@@ -1,5 +1,4 @@
 #!/usr/bin/python
-# -*- coding: utf-8 -*-
 
 ## Logistic Regression from scratch
 
diff --git a/machine_learning/sequential_minimum_optimization.py b/machine_learning/sequential_minimum_optimization.py
index aa997d88c..0612392c8 100644
--- a/machine_learning/sequential_minimum_optimization.py
+++ b/machine_learning/sequential_minimum_optimization.py
@@ -1,4 +1,3 @@
-# coding: utf-8
 """
     Implementation of sequential minimal optimization(SMO) for support vector machines(SVM).
 
@@ -29,7 +28,6 @@ Reference:
     http://web.cs.iastate.edu/~honavar/smo-svm.pdf
 """
 
-from __future__ import division
 
 import os
 import sys
@@ -44,7 +42,7 @@ from sklearn.preprocessing import StandardScaler
 CANCER_DATASET_URL = "http://archive.ics.uci.edu/ml/machine-learning-databases/breast-cancer-wisconsin/wdbc.data"
 
 
-class SmoSVM(object):
+class SmoSVM:
     def __init__(
         self,
         train,
@@ -405,7 +403,7 @@ class SmoSVM(object):
         return self.samples.shape[0]
 
 
-class Kernel(object):
+class Kernel:
     def __init__(self, kernel, degree=1.0, coef0=0.0, gamma=1.0):
         self.degree = np.float64(degree)
         self.coef0 = np.float64(coef0)
diff --git a/maths/3n+1.py b/maths/3n+1.py
index f6fe77b2b..64ff34fd2 100644
--- a/maths/3n+1.py
+++ b/maths/3n+1.py
@@ -9,9 +9,9 @@ def n31(a: int) -> Tuple[List[int], int]:
     """
 
     if not isinstance(a, int):
-        raise TypeError("Must be int, not {0}".format(type(a).__name__))
+        raise TypeError("Must be int, not {}".format(type(a).__name__))
     if a < 1:
-        raise ValueError("Given integer must be greater than 1, not {0}".format(a))
+        raise ValueError(f"Given integer must be greater than 1, not {a}")
 
     path = [a]
     while a != 1:
diff --git a/maths/__init__.py b/maths/__init__.py
index 8b1378917..e69de29bb 100644
--- a/maths/__init__.py
+++ b/maths/__init__.py
@@ -1 +0,0 @@
-
diff --git a/maths/hardy_ramanujanalgo.py b/maths/hardy_ramanujanalgo.py
index bb31a1be4..90e4913c7 100644
--- a/maths/hardy_ramanujanalgo.py
+++ b/maths/hardy_ramanujanalgo.py
@@ -37,7 +37,7 @@ def exactPrimeFactorCount(n):
 if __name__ == "__main__":
     n = 51242183
     print(f"The number of distinct prime factors is/are {exactPrimeFactorCount(n)}")
-    print("The value of log(log(n)) is {0:.4f}".format(math.log(math.log(n))))
+    print("The value of log(log(n)) is {:.4f}".format(math.log(math.log(n))))
 
     """
     The number of distinct prime factors is/are 3
diff --git a/maths/lucas_lehmer_primality_test.py b/maths/lucas_lehmer_primality_test.py
index 44e41ba58..8dac658f1 100644
--- a/maths/lucas_lehmer_primality_test.py
+++ b/maths/lucas_lehmer_primality_test.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
         In mathematics, the Lucas–Lehmer test (LLT) is a primality test for Mersenne numbers.
         https://en.wikipedia.org/wiki/Lucas%E2%80%93Lehmer_primality_test
diff --git a/maths/matrix_exponentiation.py b/maths/matrix_exponentiation.py
index c20292735..a8f114803 100644
--- a/maths/matrix_exponentiation.py
+++ b/maths/matrix_exponentiation.py
@@ -10,7 +10,7 @@ https://www.hackerearth.com/practice/notes/matrix-exponentiation-1/
 """
 
 
-class Matrix(object):
+class Matrix:
     def __init__(self, arg):
         if isinstance(arg, list):  # Initialzes a matrix identical to the one provided.
             self.t = arg
diff --git a/maths/newton_raphson.py b/maths/newton_raphson.py
index 093cc4438..c4975c73e 100644
--- a/maths/newton_raphson.py
+++ b/maths/newton_raphson.py
@@ -52,4 +52,4 @@ if __name__ == "__main__":
     plt.xlabel("step")
     plt.ylabel("error")
     plt.show()
-    print("solution = {%f}, error = {%f}" % (solution, error))
+    print(f"solution = {{{solution:f}}}, error = {{{error:f}}}")
diff --git a/maths/pythagoras.py b/maths/pythagoras.py
index 2f59107cd..69a17731a 100644
--- a/maths/pythagoras.py
+++ b/maths/pythagoras.py
@@ -14,7 +14,7 @@ class Point:
 
 
 def distance(a: Point, b: Point) -> float:
-    return math.sqrt(abs(((b.x - a.x) ** 2 + (b.y - a.y) ** 2 + (b.z - a.z) ** 2)))
+    return math.sqrt(abs((b.x - a.x) ** 2 + (b.y - a.y) ** 2 + (b.z - a.z) ** 2))
 
 
 def test_distance() -> None:
diff --git a/maths/sieve_of_eratosthenes.py b/maths/sieve_of_eratosthenes.py
index 44c7f8a02..4761c9339 100644
--- a/maths/sieve_of_eratosthenes.py
+++ b/maths/sieve_of_eratosthenes.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 """
 Sieve of Eratosthones
 
diff --git a/matrix/matrix_operation.py b/matrix/matrix_operation.py
index 5ca61b4ed..26e21aafc 100644
--- a/matrix/matrix_operation.py
+++ b/matrix/matrix_operation.py
@@ -148,9 +148,9 @@ def main():
         % (matrix_a, matrix_b, multiply(matrix_a, matrix_b))
     )
     print("Identity:  %s \n" % identity(5))
-    print("Minor of %s = %s \n" % (matrix_c, minor(matrix_c, 1, 2)))
-    print("Determinant of %s = %s \n" % (matrix_b, determinant(matrix_b)))
-    print("Inverse of %s = %s\n" % (matrix_d, inverse(matrix_d)))
+    print("Minor of {} = {} \n".format(matrix_c, minor(matrix_c, 1, 2)))
+    print("Determinant of {} = {} \n".format(matrix_b, determinant(matrix_b)))
+    print("Inverse of {} = {}\n".format(matrix_d, inverse(matrix_d)))
 
 
 if __name__ == "__main__":
diff --git a/matrix/rotate_matrix.py b/matrix/rotate_matrix.py
index 822851826..14a9493cd 100644
--- a/matrix/rotate_matrix.py
+++ b/matrix/rotate_matrix.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 """
 In this problem, we want to rotate the matrix elements by 90, 180, 270 (counterclockwise)
 Discussion in stackoverflow:
diff --git a/matrix/searching_in_sorted_matrix.py b/matrix/searching_in_sorted_matrix.py
index 1b3eeedf3..3897ffb1d 100644
--- a/matrix/searching_in_sorted_matrix.py
+++ b/matrix/searching_in_sorted_matrix.py
@@ -2,7 +2,7 @@ def search_in_a_sorted_matrix(mat, m, n, key):
     i, j = m - 1, 0
     while i >= 0 and j < n:
         if key == mat[i][j]:
-            print("Key %s found at row- %s column- %s" % (key, i + 1, j + 1))
+            print("Key {} found at row- {} column- {}".format(key, i + 1, j + 1))
             return
         if key < mat[i][j]:
             i -= 1
diff --git a/matrix/sherman_morrison.py b/matrix/sherman_morrison.py
index 531b76cde..257cf3371 100644
--- a/matrix/sherman_morrison.py
+++ b/matrix/sherman_morrison.py
@@ -176,7 +176,7 @@ class Matrix:
             return result
         else:
             raise TypeError(
-                "Unsupported type given for another (%s)" % (type(another),)
+                "Unsupported type given for another ({})".format(type(another))
             )
 
     def transpose(self):
@@ -248,17 +248,17 @@ if __name__ == "__main__":
         ainv = Matrix(3, 3, 0)
         for i in range(3):
             ainv[i, i] = 1
-        print("a^(-1) is %s" % (ainv,))
+        print(f"a^(-1) is {ainv}")
         # u, v
         u = Matrix(3, 1, 0)
         u[0, 0], u[1, 0], u[2, 0] = 1, 2, -3
         v = Matrix(3, 1, 0)
         v[0, 0], v[1, 0], v[2, 0] = 4, -2, 5
-        print("u is %s" % (u,))
-        print("v is %s" % (v,))
+        print(f"u is {u}")
+        print(f"v is {v}")
         print("uv^T is %s" % (u * v.transpose()))
         # Sherman Morrison
-        print("(a + uv^T)^(-1) is %s" % (ainv.ShermanMorrison(u, v),))
+        print("(a + uv^T)^(-1) is {}".format(ainv.ShermanMorrison(u, v)))
 
     def test2():
         import doctest
diff --git a/neural_network/back_propagation_neural_network.py b/neural_network/back_propagation_neural_network.py
index 224fc85de..c771dc46a 100644
--- a/neural_network/back_propagation_neural_network.py
+++ b/neural_network/back_propagation_neural_network.py
@@ -1,5 +1,4 @@
 #!/usr/bin/python
-# encoding=utf8
 
 """
 
@@ -31,6 +30,7 @@ class DenseLayer:
     """
     Layers of BP neural network
     """
+
     def __init__(
         self, units, activation=None, learning_rate=None, is_input_layer=False
     ):
@@ -99,6 +99,7 @@ class BPNN:
     """
     Back Propagation Neural Network model
     """
+
     def __init__(self):
         self.layers = []
         self.train_mse = []
diff --git a/neural_network/convolution_neural_network.py b/neural_network/convolution_neural_network.py
index 9448671ab..ecc8e3392 100644
--- a/neural_network/convolution_neural_network.py
+++ b/neural_network/convolution_neural_network.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 """
      - - - - - -- - - - - - - - - - - - - - - - - - - - - - -
     Name - - CNN - Convolution Neural Network For Photo Recognizing
@@ -286,7 +284,7 @@ class CNN:
                 self.thre_bp3 = self.thre_bp3 - pd_k_all * self.rate_thre
                 self.thre_bp2 = self.thre_bp2 - pd_j_all * self.rate_thre
                 # calculate the sum error of all single image
-                errors = np.sum(abs((data_teach - bp_out3)))
+                errors = np.sum(abs(data_teach - bp_out3))
                 alle = alle + errors
                 # print('   ----Teach      ',data_teach)
                 # print('   ----BP_output  ',bp_out3)
diff --git a/neural_network/input_data.py b/neural_network/input_data.py
index ea826be6c..0e22ac0bc 100644
--- a/neural_network/input_data.py
+++ b/neural_network/input_data.py
@@ -17,9 +17,6 @@
 This module and all its submodules are deprecated.
 """
 
-from __future__ import absolute_import
-from __future__ import division
-from __future__ import print_function
 
 import collections
 import gzip
@@ -115,7 +112,7 @@ def _extract_labels(f, one_hot=False, num_classes=10):
         return labels
 
 
-class _DataSet(object):
+class _DataSet:
     """Container class for a _DataSet (deprecated).
 
   THIS CLASS IS DEPRECATED.
@@ -165,7 +162,7 @@ class _DataSet(object):
         else:
             assert (
                 images.shape[0] == labels.shape[0]
-            ), "images.shape: %s labels.shape: %s" % (images.shape, labels.shape)
+            ), f"images.shape: {images.shape} labels.shape: {labels.shape}"
             self._num_examples = images.shape[0]
 
             # Convert shape from [num examples, rows, columns, depth]
diff --git a/other/anagrams.py b/other/anagrams.py
index 9e103296b..6e6806e92 100644
--- a/other/anagrams.py
+++ b/other/anagrams.py
@@ -4,7 +4,7 @@ start_time = time.time()
 print("creating word list...")
 path = os.path.split(os.path.realpath(__file__))
 with open(path[0] + "/words") as f:
-    word_list = sorted(list(set([word.strip().lower() for word in f])))
+    word_list = sorted(list({word.strip().lower() for word in f}))
 
 
 def signature(word):
diff --git a/other/fischer_yates_shuffle.py b/other/fischer_yates_shuffle.py
index 977e5f131..4217cb0be 100644
--- a/other/fischer_yates_shuffle.py
+++ b/other/fischer_yates_shuffle.py
@@ -1,5 +1,4 @@
 #!/usr/bin/python
-# encoding=utf8
 """
 The Fisher–Yates shuffle is an algorithm for generating a random permutation of a finite sequence.
 For more details visit
diff --git a/other/linear_congruential_generator.py b/other/linear_congruential_generator.py
index 3b150f422..ea0adc7d0 100644
--- a/other/linear_congruential_generator.py
+++ b/other/linear_congruential_generator.py
@@ -3,7 +3,7 @@ __author__ = "Tobias Carryer"
 from time import time
 
 
-class LinearCongruentialGenerator(object):
+class LinearCongruentialGenerator:
     """
     A pseudorandom number generator.
     """
diff --git a/other/primelib.py b/other/primelib.py
index 6fc5eddeb..ff438755a 100644
--- a/other/primelib.py
+++ b/other/primelib.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Created on Thu Oct  5 16:44:23 2017
 
diff --git a/other/sierpinski_triangle.py b/other/sierpinski_triangle.py
index 0e6ce43e3..a262900a8 100644
--- a/other/sierpinski_triangle.py
+++ b/other/sierpinski_triangle.py
@@ -1,5 +1,4 @@
 #!/usr/bin/python
-# encoding=utf8
 
 """Author Anurag Kumar | anuragkumarak95@gmail.com | git/anuragkumarak95
 
diff --git a/project_euler/problem_06/sol1.py b/project_euler/problem_06/sol1.py
index c69b6c89e..513b35467 100644
--- a/project_euler/problem_06/sol1.py
+++ b/project_euler/problem_06/sol1.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Problem:
 
diff --git a/project_euler/problem_06/sol2.py b/project_euler/problem_06/sol2.py
index 1698a3fb6..18cdb5175 100644
--- a/project_euler/problem_06/sol2.py
+++ b/project_euler/problem_06/sol2.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Problem:
 
diff --git a/project_euler/problem_06/sol3.py b/project_euler/problem_06/sol3.py
index f9c5dacb3..ee739c9a1 100644
--- a/project_euler/problem_06/sol3.py
+++ b/project_euler/problem_06/sol3.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Problem:
 
diff --git a/project_euler/problem_06/sol4.py b/project_euler/problem_06/sol4.py
index 1e1de5570..07eed57ba 100644
--- a/project_euler/problem_06/sol4.py
+++ b/project_euler/problem_06/sol4.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Problem:
 
diff --git a/project_euler/problem_07/sol1.py b/project_euler/problem_07/sol1.py
index d8d67e157..f6b2584d9 100644
--- a/project_euler/problem_07/sol1.py
+++ b/project_euler/problem_07/sol1.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 By listing the first six prime numbers:
 
diff --git a/project_euler/problem_07/sol2.py b/project_euler/problem_07/sol2.py
index 5d30e540b..6bfc5881f 100644
--- a/project_euler/problem_07/sol2.py
+++ b/project_euler/problem_07/sol2.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 By listing the first six prime numbers:
 
diff --git a/project_euler/problem_07/sol3.py b/project_euler/problem_07/sol3.py
index 3c28ecf7f..9b02ea87e 100644
--- a/project_euler/problem_07/sol3.py
+++ b/project_euler/problem_07/sol3.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 By listing the first six prime numbers:
 
diff --git a/project_euler/problem_08/sol1.py b/project_euler/problem_08/sol1.py
index 6752fae3d..e7582d46c 100644
--- a/project_euler/problem_08/sol1.py
+++ b/project_euler/problem_08/sol1.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 The four adjacent digits in the 1000-digit number that have the greatest
 product are 9 × 9 × 8 × 9 = 5832.
diff --git a/project_euler/problem_08/sol2.py b/project_euler/problem_08/sol2.py
index bae96e373..bf8afa837 100644
--- a/project_euler/problem_08/sol2.py
+++ b/project_euler/problem_08/sol2.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 The four adjacent digits in the 1000-digit number that have the greatest
 product are 9 × 9 × 8 × 9 = 5832.
diff --git a/project_euler/problem_08/sol3.py b/project_euler/problem_08/sol3.py
index fe9901742..dfbef5755 100644
--- a/project_euler/problem_08/sol3.py
+++ b/project_euler/problem_08/sol3.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 The four adjacent digits in the 1000-digit number that have the greatest
 product are 9 × 9 × 8 × 9 = 5832.
diff --git a/project_euler/problem_14/sol1.py b/project_euler/problem_14/sol1.py
index ab09937fb..fda45bc94 100644
--- a/project_euler/problem_14/sol1.py
+++ b/project_euler/problem_14/sol1.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Problem Statement:
 The following iterative sequence is defined for the set of positive integers:
diff --git a/project_euler/problem_14/sol2.py b/project_euler/problem_14/sol2.py
index 9b8857e71..375a34c72 100644
--- a/project_euler/problem_14/sol2.py
+++ b/project_euler/problem_14/sol2.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Collatz conjecture: start with any positive integer n. Next term obtained from
 the previous term as follows:
diff --git a/project_euler/problem_21/sol1.py b/project_euler/problem_21/sol1.py
index 49c2db964..f01c9d0da 100644
--- a/project_euler/problem_21/sol1.py
+++ b/project_euler/problem_21/sol1.py
@@ -1,4 +1,3 @@
-# -.- coding: latin-1 -.-
 from math import sqrt
 
 """
diff --git a/project_euler/problem_22/sol1.py b/project_euler/problem_22/sol1.py
index f6275e213..982906245 100644
--- a/project_euler/problem_22/sol1.py
+++ b/project_euler/problem_22/sol1.py
@@ -1,4 +1,3 @@
-# -*- coding: latin-1 -*-
 """
 Name scores
 Problem 22
diff --git a/project_euler/problem_22/sol2.py b/project_euler/problem_22/sol2.py
index 69acd2fb8..5ae41c846 100644
--- a/project_euler/problem_22/sol2.py
+++ b/project_euler/problem_22/sol2.py
@@ -1,4 +1,3 @@
-# -*- coding: latin-1 -*-
 """
 Name scores
 Problem 22
diff --git a/project_euler/problem_25/sol1.py b/project_euler/problem_25/sol1.py
index 8fce32285..f0228915d 100644
--- a/project_euler/problem_25/sol1.py
+++ b/project_euler/problem_25/sol1.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 The Fibonacci sequence is defined by the recurrence relation:
 
diff --git a/project_euler/problem_25/sol2.py b/project_euler/problem_25/sol2.py
index d754e2ddd..c98f09b1d 100644
--- a/project_euler/problem_25/sol2.py
+++ b/project_euler/problem_25/sol2.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 The Fibonacci sequence is defined by the recurrence relation:
 
diff --git a/project_euler/problem_25/sol3.py b/project_euler/problem_25/sol3.py
index 4e3084ce5..4a1d9da76 100644
--- a/project_euler/problem_25/sol3.py
+++ b/project_euler/problem_25/sol3.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 The Fibonacci sequence is defined by the recurrence relation:
 
diff --git a/project_euler/problem_31/sol1.py b/project_euler/problem_31/sol1.py
index 187fb9167..1c59658b8 100644
--- a/project_euler/problem_31/sol1.py
+++ b/project_euler/problem_31/sol1.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
 Coin sums
 Problem 31
diff --git a/project_euler/problem_32/sol32.py b/project_euler/problem_32/sol32.py
index 0abc04829..393218339 100644
--- a/project_euler/problem_32/sol32.py
+++ b/project_euler/problem_32/sol32.py
@@ -46,13 +46,11 @@ def solution():
     """
 
     return sum(
-        set(
-            [
-                int("".join(pandigital[5:9]))
-                for pandigital in itertools.permutations("123456789")
-                if isCombinationValid(pandigital)
-            ]
-        )
+        {
+            int("".join(pandigital[5:9]))
+            for pandigital in itertools.permutations("123456789")
+            if isCombinationValid(pandigital)
+        }
     )
 
 
diff --git a/project_euler/problem_33/__init__.py b/project_euler/problem_33/__init__.py
index 8b1378917..e69de29bb 100644
--- a/project_euler/problem_33/__init__.py
+++ b/project_euler/problem_33/__init__.py
@@ -1 +0,0 @@
-
diff --git a/project_euler/problem_33/sol1.py b/project_euler/problem_33/sol1.py
index 0992c9693..73a49023a 100644
--- a/project_euler/problem_33/sol1.py
+++ b/project_euler/problem_33/sol1.py
@@ -43,7 +43,7 @@ def solve(digit_len: int) -> str:
         while den <= 99:
             if (num != den) and (num % 10 == den // 10) and (den % 10 != 0):
                 if isDigitCancelling(num, den):
-                    solutions.append("{}/{}".format(num, den))
+                    solutions.append(f"{num}/{den}")
             den += 1
         num += 1
         den = 10
diff --git a/project_euler/problem_40/sol1.py b/project_euler/problem_40/sol1.py
index 786725e27..69be37772 100644
--- a/project_euler/problem_40/sol1.py
+++ b/project_euler/problem_40/sol1.py
@@ -1,4 +1,3 @@
-# -.- coding: latin-1 -.-
 """
 Champernowne's constant
 Problem 40
diff --git a/project_euler/problem_53/sol1.py b/project_euler/problem_53/sol1.py
index f17508b00..0692bbe0e 100644
--- a/project_euler/problem_53/sol1.py
+++ b/project_euler/problem_53/sol1.py
@@ -1,4 +1,3 @@
-# -.- coding: latin-1 -.-
 """
 Combinatoric selections
 Problem 53
diff --git a/sorts/external_sort.py b/sorts/external_sort.py
index abdcb29f9..e5b2c045f 100644
--- a/sorts/external_sort.py
+++ b/sorts/external_sort.py
@@ -7,7 +7,7 @@ import os
 import argparse
 
 
-class FileSplitter(object):
+class FileSplitter:
     BLOCK_FILENAME_FORMAT = "block_{0}.dat"
 
     def __init__(self, filename):
@@ -44,7 +44,7 @@ class FileSplitter(object):
         map(lambda f: os.remove(f), self.block_filenames)
 
 
-class NWayMerge(object):
+class NWayMerge:
     def select(self, choices):
         min_index = -1
         min_str = None
@@ -56,7 +56,7 @@ class NWayMerge(object):
         return min_index
 
 
-class FilesArray(object):
+class FilesArray:
     def __init__(self, files):
         self.files = files
         self.empty = set()
@@ -89,7 +89,7 @@ class FilesArray(object):
         return value
 
 
-class FileMerger(object):
+class FileMerger:
     def __init__(self, merge_strategy):
         self.merge_strategy = merge_strategy
 
@@ -109,7 +109,7 @@ class FileMerger(object):
         return files
 
 
-class ExternalSort(object):
+class ExternalSort:
     def __init__(self, block_size):
         self.block_size = block_size
 
diff --git a/strings/aho-corasick.py b/strings/aho-corasick.py
index b2f89450e..d63dc94a0 100644
--- a/strings/aho-corasick.py
+++ b/strings/aho-corasick.py
@@ -82,7 +82,7 @@ class Automaton:
                 for key in self.adlist[current_state]["output"]:
                     if not (key in result):
                         result[key] = []
-                    result[key].append((i - len(key) + 1))
+                    result[key].append(i - len(key) + 1)
         return result