June 2018 Update

Task/24-game-Solve/Python/24-game-solve-3.py

@@ -0,0 +1,44 @@
+# -*- coding: utf-8 -*-
+# Python 3
+from operator import mul, sub, add
+
+
+def div(a, b):
+    if b == 0:
+        return 999999.0
+    return a / b
+
+ops = {mul: '*', div: '/', sub: '-', add: '+'}
+
+def solve24(num, how, target):
+    if len(num) == 1:
+        if round(num[0], 5) == round(target, 5):
+            yield str(how[0]).replace(',', '').replace("'", '')
+    else:
+        for i, n1 in enumerate(num):
+            for j, n2 in enumerate(num):
+                if i != j:
+                    for op in ops:
+                        new_num = [n for k, n in enumerate(num) if k != i and k != j] + [op(n1, n2)]
+                        new_how = [h for k, h in enumerate(how) if k != i and k != j] + [(how[i], ops[op], how[j])]
+                        yield from solve24(new_num, new_how, target)
+
+tests = [
+         [1, 7, 2, 7],
+         [5, 7, 5, 4],
+         [1, 4, 6, 6],
+         [2, 3, 7, 3],
+         [1, 6, 2, 6],
+         [7, 9, 4, 1],
+         [6, 4, 2, 2],
+         [5, 7, 9, 7],
+         [3, 3, 8, 8],  # Difficult case requiring precise division
+         [8, 7, 9, 7],  # No solution
+         [9, 4, 4, 5],  # No solution
+            ]
+for nums in tests:
+    print(nums, end=' : ')
+    try:
+        print(next(solve24(nums, nums, 24)))
+    except StopIteration:
+        print("No solution found")