Fix readme and duplicate (#967)

* Fix typo

* Add all_permutations algorithm to backtracking directory

* Update backtracking and D&C algorithms in README

Update backtracking and divide_and_conquer algorithms in README

* Remove the duplicated file

README.md

@@ -45,6 +45,8 @@ We're on [Gitter](https://gitter.im/TheAlgorithms)! Please join us.
 
 - [N Queens](./backtracking/n_queens.py)
 - [Sum Of Subsets](./backtracking/sum_of_subsets.py)
+- [All Subsequences](./backtracking/all_subsequences.py)
+- [All Permutations](./backtracking/all_permutations.py)
 
 ## Ciphers
 
@@ -220,7 +222,6 @@ We're on [Gitter](https://gitter.im/TheAlgorithms)! Please join us.
 ## Divide And Conquer
 
 - [Max Subarray Sum](./divide_and_conquer/max_subarray_sum.py)
-- [Max Sub Array Sum](./divide_and_conquer/max_sub_array_sum.py)
 - [Closest Pair Of Points](./divide_and_conquer/closest_pair_of_points.py)
 
 ## Strings

divide_and_conquer/max_sub_array_sum.py

@@ -1,72 +0,0 @@
-""" 
-Given a array of length n, max_sub_array_sum() finds the maximum of sum of contiguous sub-array using divide and conquer method.
-
-Time complexity : O(n log n)
-
-Ref : INTRODUCTION TO ALGORITHMS THIRD EDITION (section : 4, sub-section : 4.1, page : 70)
-
-"""
-
-
-def max_sum_from_start(array):
-    """ This function finds the maximum contiguous sum of array from 0 index
-
-    Parameters : 
-    array (list[int]) : given array
-    
-    Returns : 
-    max_sum (int) : maximum contiguous sum of array from 0 index
-
-    """
-    array_sum = 0
-    max_sum = float("-inf")
-    for num in array:
-        array_sum += num
-        if array_sum > max_sum:
-            max_sum = array_sum
-    return max_sum
-
-
-def max_cross_array_sum(array, left, mid, right):
-    """ This function finds the maximum contiguous sum of left and right arrays
-
-    Parameters : 
-    array, left, mid, right (list[int], int, int, int) 
-    
-    Returns : 
-    (int) :  maximum of sum of contiguous sum of left and right arrays
-
-    """
-
-    max_sum_of_left = max_sum_from_start(array[left:mid+1][::-1])
-    max_sum_of_right = max_sum_from_start(array[mid+1: right+1])
-    return max_sum_of_left + max_sum_of_right
-
-
-def max_sub_array_sum(array, left, right):
-    """ This function finds the maximum of sum of contiguous sub-array using divide and conquer method
-
-    Parameters : 
-    array, left, right (list[int], int, int) : given array, current left index and current right index
-    
-    Returns : 
-    int :  maximum of sum of contiguous sub-array
-
-    """
-
-    # base case: array has only one element
-    if left == right:
-        return array[right]
-    
-    # Recursion
-    mid = (left + right) // 2
-    left_half_sum = max_sub_array_sum(array, left, mid)
-    right_half_sum = max_sub_array_sum(array, mid + 1, right)
-    cross_sum = max_cross_array_sum(array, left, mid, right)
-    return max(left_half_sum, right_half_sum, cross_sum)
-
-
-array = [-2, -5, 6, -2, -3, 1, 5, -6]
-array_length = len(array)
-print("Maximum sum of contiguous subarray:", max_sub_array_sum(array, 0, array_length - 1))
-