Solve problem 961

python/e961.py

@@ -0,0 +1,50 @@
+from functools import cache
+
+
+@cache
+def remove(n: str, pos: int) -> str:
+    assert pos < len(n)
+    r = n[:pos] + n[pos + 1:]
+    r = r.lstrip("0")
+    return r
+
+
+@cache
+def player_wins(n: str) -> bool:
+    if len(n) == 1:
+        return True
+    for i in range(len(n)):
+        if not player_wins(remove(n, i)):
+            return True
+    return False
+
+def w(n: int) -> int:
+    r = 0
+    xs = [("", 0)]
+    for _ in range(n):
+        nxs = []
+        for x, x_count in xs:
+            nxs.append(("0" + x, x_count))
+            nx, nx_count = "x" + x, x_count + 1
+            if player_wins(nx):
+                r += (9 ** nx_count)
+            nxs.append((nx, nx_count))
+        xs = nxs
+    return r
+
+
+def euler_961():
+    assert remove("105", 0) == "5"
+    assert remove("105", 1) == "15"
+    assert remove("105", 2) == "10"
+    assert remove("10005", 0) == "5"
+    assert w(2) == 18
+    assert w(4) == 1656
+    return w(18)
+
+
+if __name__ == "__main__":
+    solution = euler_961()
+    print("e961.py: " + str(solution))
+    # assert(solution == 0)
+

python/lib_create_templates.py

@@ -7,7 +7,7 @@ def euler_XXX():
 
 if __name__ == "__main__":
     solution = euler_XXX()
-    print("eXXX.py: " + str(solution))
+    print(f"eXXX.py: {solution}")
     # assert(solution == 0)
 
 """