Add Project Euler Problem 80 (#2885)

* adding solution to problem 80

* updating DIRECTORY.md

* fixing spell check

* updating sol as per comments

* Add reference link to the problem

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: Dhruv <dhruvmanila@gmail.com>

DIRECTORY.md

@@ -662,6 +662,8 @@
     * [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_71/sol1.py)
   * Problem 76
     * [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_76/sol1.py)
+  * Problem 80
+    * [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_80/sol1.py)
   * Problem 97
     * [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_97/sol1.py)
   * Problem 99

project_euler/problem_80/sol1.py

@@ -0,0 +1,37 @@
+"""
+Project Euler Problem 80: https://projecteuler.net/problem=80
+Author: Sandeep Gupta
+Problem statement: For the first one hundred natural numbers, find the total of
+the digital sums of the first one hundred decimal digits for all the irrational
+square roots.
+Time: 5 October 2020, 18:30
+"""
+import decimal
+
+
+def solution() -> int:
+    """
+    To evaluate the sum, Used decimal python module to calculate the decimal
+    places up to 100, the most important thing would be take calculate
+    a few extra places for decimal otherwise there will be rounding
+    error.
+
+    >>> solution()
+    40886
+    """
+    answer = 0
+    decimal_context = decimal.Context(prec=105)
+    for i in range(2, 100):
+        number = decimal.Decimal(i)
+        sqrt_number = number.sqrt(decimal_context)
+        if len(str(sqrt_number)) > 1:
+            answer += int(str(sqrt_number)[0])
+            sqrt_number = str(sqrt_number)[2:101]
+            answer += sum([int(x) for x in sqrt_number])
+    return answer
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()