added solution 7 for problem_01 (#1416)

* added solution 7 for problem_01

* added solution 5 for problem_02

project_euler/problem_01/sol7.py

@@ -0,0 +1,32 @@
+"""
+Problem Statement:
+If we list all the natural numbers below 10 that are multiples of 3 or 5,
+we get 3,5,6 and 9. The sum of these multiples is 23.
+Find the sum of all the multiples of 3 or 5 below N.
+"""
+
+
+def solution(n):
+    """Returns the sum of all the multiples of 3 or 5 below n.
+
+    >>> solution(3)
+    0
+    >>> solution(4)
+    3
+    >>> solution(10)
+    23
+    >>> solution(600)
+    83700
+    """
+
+    result = 0
+    for i in range(n):
+        if i % 3 == 0:
+            result += i
+        elif i % 5 == 0:
+            result += i
+    return result
+
+
+if __name__ == "__main__":
+    print(solution(int(input().strip())))