Add initial version of file for the Euler project problem 136 solution.

Author: mindaugl

project_euler/problem_136/__init__.py

@@ -0,0 +1,23 @@
+N = 50000000
+
+
+def solution(n_limit: int = N) -> int:
+    n_sol = [0] * n_limit
+
+    for delta in range(1, (n_limit + 1) // 4):
+        for y in range(4 * delta - 1, delta, -1):
+            n = y * (4 * delta - y)
+            if n >= n_limit:
+                break
+            n_sol[n] += 1
+
+    ans = 0
+    for i in range(n_limit):
+        if n_sol[i] == 1:
+            ans += 1
+
+    return ans
+
+
+if __name__ == "__main__":
+    print(f"{solution() = }")