LeetCode刷题（C++）——Construct Binary Tree from Inorder and Postorder Traversal（Normal）

题目描述

Given inorder and postorder traversal of a tree, construct the binary tree.

Note:

You may assume that duplicates do not exist in the tree.

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    TreeNode* buildTree(vector<int>& inorder, vector<int>& postorder) {        if (inorder.size() == 0 || postorder.size() == 0 || inorder.size() != postorder.size())return NULL;return dfs(inorder, 0, inorder.size() - 1, postorder, 0, postorder.size() - 1);}TreeNode* dfs(vector<int>&inorder, int l1, int r1, vector<int>& postorder, int l2, int r2){if (l2 > r2)return NULL;if (l2 == r2)return new TreeNode(postorder[r2]);TreeNode* root = new TreeNode(postorder[r2]);for (int i = 0; i < inorder.size();i++){if (inorder[i] == postorder[r2]){root->left = dfs(inorder, l1, i - 1, postorder, l2, l2 + i - l1-1);root->right = dfs(inorder, i + 1, r1, postorder, l2 + i - l1, r2 - 1);return root;}}return NULL;    }};