Another dummy solution which takes time to finish

Author: dhruvmanila

project_euler/problem_014/sol3.py

@@ -0,0 +1,60 @@
+"""
+Problem 14: https://projecteuler.net/problem=14
+
+Problem Statement:
+The following iterative sequence is defined for the set of positive integers:
+
+    n → n/2 (n is even)
+    n → 3n + 1 (n is odd)
+
+Using the rule above and starting with 13, we generate the following sequence:
+
+    13 → 40 → 20 → 10 → 5 → 16 → 8 → 4 → 2 → 1
+
+It can be seen that this sequence (starting at 13 and finishing at 1) contains
+10 terms. Although it has not been proved yet (Collatz Problem), it is thought
+that all starting numbers finish at 1.
+
+Which starting number, under one million, produces the longest chain?
+"""
+
+
+def solution(n: int = 1000000) -> int:
+    """Returns the number under n that generates the longest sequence using the
+    formula:
+    n → n/2 (n is even)
+    n → 3n + 1 (n is odd)
+
+    # The code below has been commented due to slow execution affecting Travis.
+    # >>> solution(1000000)
+    # 837799
+    >>> solution(200)
+    171
+    >>> solution(5000)
+    3711
+    >>> solution(15000)
+    13255
+    """
+    largest_number = 0
+    pre_counter = 0
+
+    for input1 in range(n):
+        counter = 1
+        number = input1
+
+        while number > 1:
+            if number % 2 == 0:
+                number /= 2
+                counter += 1
+            else:
+                number = (3 * number) + 1
+                counter += 1
+
+        if counter > pre_counter:
+            largest_number = input1
+            pre_counter = counter
+    return largest_number
+
+
+if __name__ == "__main__":
+    print(solution(int(input().strip())))