Add second solution for the Euler project problem 13.

Author: mindaugl

project_euler/problem_013/sol2.py

@@ -0,0 +1,41 @@
+"""
+Problem 13: https://projecteuler.net/problem=13
+
+Problem Statement:
+Work out the first ten digits of the sum of the following one-hundred 50-digit
+numbers.
+"""
+
+import os
+
+
+def solution(n: int = 10) -> str:
+    """
+    Returns the first 'n' digits of the sum of the array elements
+    from the file num.txt. n should be larger than 2.
+
+    >>> solution(3)
+    '553'
+    >>> solution(6)
+    '553737'
+    """
+    file_path = os.path.join(os.path.dirname(__file__), "num.txt")
+    numbers: list[str] = []
+    with open(file_path) as file_hand:
+        for line in file_hand:
+            numbers.append(line)
+
+    ans = [0] * 50
+    for d in range(49, -1, -1):
+        for num in numbers:
+            ans[d] += int(num[d])
+        if d > 0:
+            ans[d - 1] = ans[d] // 10
+            ans[d] %= 10
+
+    size_first = len(str(ans[0]))
+    return "".join([str(x) for x in ans[: n - size_first + 1]])
+
+
+if __name__ == "__main__":
+    print(solution())