This is the problem that I want to solve. However, I cannot figure out why the pointer of ans is changed in recursion function but is still the same in the main function. Could anyone points out where the problem is? LeetCode problem: Find a Corresponding Node of a Binary Tree in a Clone of That Tree class Solution: def getTargetCopy(self, original: TreeNode, cloned: TreeNode, target: TreeNode) -> TreeNode: # the helper dfs function def dfs(root): if not root: return if root.val == target.val: ans = root return dfs(root.left) dfs(root.right) # main function ans = TreeNode(0) dfs(cloned) return ans Also, I have tried changing return ans to return ans.right and it works. Still don't understand why it works but the upper one cannot work class Solution: def getTargetCopy(self, original: TreeNode, cloned: TreeNode, target: TreeNode) -> TreeNode: # the helper dfs function def dfs(root): if not root: return if root.val == target.val: ans.right = root return dfs(root.left) dfs(root.right) # main function ans = TreeNode(0) dfs(cloned) return ans.right Continue reading...
