problem: 0113 path sum

Author: cychiu8

0113 Path Sum II/0113 Path Sum II.md

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+# 0113. Path Sum II
+
+
+* Difficulty: medium
+* Link: https://leetcode.com/problems/path-sum-ii/
+* Topics: DFS-BFS
+
+# Clarification
+
+1. Check the inputs and outputs
+
+# Solution
+
+### Thought Process
+
+1. traverse all path by DFS and compare the sum
+- Implement
+    
+    ```python
+    # Definition for a binary tree node.
+    # class TreeNode:
+    #     def __init__(self, val=0, left=None, right=None):
+    #         self.val = val
+    #         self.left = left
+    #         self.right = right
+    class Solution:
+        def pathSum(self, root: Optional[TreeNode], targetSum: int) -> List[List[int]]:
+            result = []
+            if not root:
+                return result
+            
+            def dfs(current, path, res):
+                path.append(current.val)
+                res -= current.val
+                if not current.left and not current.right:
+                    if res == 0:
+                        return result.append(path[:])
+                if current.left:
+                    dfs(current.left, path[:], res)
+                if current.right:
+                    dfs(current.right, path[:], res)
+                
+            dfs(root, [], targetSum)
+            return result
+    ```
+    
+
+### Complexity
+
+- Time complexity:
+- Space complexity: