Dec 26

Author: siddydutta

2024-12-December-LeetCoding-Challenge/README.md

@@ -28,7 +28,7 @@
 | December 23 | [2471. Minimum Number of Operations to Sort a Binary Tree by Level](https://leetcode.com/problems/minimum-number-of-operations-to-sort-a-binary-tree-by-level/) | Medium | Solved |
 | December 24 | [3203. Find Minimum Diameter After Merging Two Trees](https://leetcode.com/problems/find-minimum-diameter-after-merging-two-trees/) | Hard | Unsolved |
 | December 25 | [515. Find Largest Value in Each Tree Row](https://leetcode.com/problems/find-largest-value-in-each-tree-row/) | Medium | Solved |
-| December 26 | []() |  |  |
+| December 26 | [494. Target Sum](https://leetcode.com/problems/target-sum/) | Medium | Solved |
 | December 27 | []() |  |  |
 | December 28 | []() |  |  |
 | December 29 | []() |  |  |
@@ -39,5 +39,5 @@
 | Level  | Problems | Solved | Unsolved |
 | ---    | --- | --- | --- |
 | Easy   | 5 | 5 | 0 |
-| Medium | 17 | 11 | 6 |
+| Medium | 18 | 12 | 6 |
 | Hard   | 3 | 0 | 3 |

2024-12-December-LeetCoding-Challenge/Target Sum.py

@@ -0,0 +1,26 @@
+from functools import lru_cache
+from typing import List
+
+
+class Solution:
+    def findTargetSumWays(self, nums: List[int], target: int) -> int:
+        @lru_cache(None)
+        def dfs(idx: int = 0, curr_sum: int = 0) -> int:
+            if idx == len(nums):
+                return curr_sum == target
+            return dfs(idx+1, curr_sum+nums[idx]) + dfs(idx+1, curr_sum-nums[idx])
+        return dfs()
+
+
+def main():
+    nums = [1, 1, 1, 1, 1]
+    target = 3
+    assert Solution().findTargetSumWays(nums, target) == 5
+
+    nums = [1]
+    target = 1
+    assert Solution().findTargetSumWays(nums, target) == 1
+
+
+if __name__ == '__main__':
+    main()