重建二叉树

题目

输入二叉树的先序遍历和中序遍历，重建一课二叉树

代码

#include<iostream>#include<vector>using namespace std;/* Definition for binary tree*/struct TreeNode {    int val;    TreeNode *left;    TreeNode *right;    TreeNode(int x) : val(x), left(NULL), right(NULL) {}};class Solution {public:    TreeNode* reConstructBinaryTree(vector<int> pre, vector<int> vin) {        TreeNode *root=new TreeNode(pre[0]);//必须使用new或malloc，否则局部变量会在下一循环被删除        vector<int> vinLeft, vinRight;        bool isLeft = true;        //根据前序pre第一个元素将中序分成两部分        for (int i = 0; i<vin.size(); i++){            if (vin[i] == pre[0]){                isLeft = false;                continue;            }            if (isLeft) vinLeft.push_back(vin[i]);            else vinRight.push_back(vin[i]);        }        vector<int> preLeft, preRight;        //根据中序左右两部分大小将前序分成两部分        for (int i = 1; i<pre.size(); i++){            if (i <= vinLeft.size()) preLeft.push_back(pre[i]);            else preRight.push_back(pre[i]);        }        //左子树迭代        if (vinLeft.size() == 0) root->left = NULL;        else root->left = reConstructBinaryTree(preLeft, vinLeft);        //右子树迭代        if (vinRight.size() == 0) root->right = NULL;        else root->right = reConstructBinaryTree(preRight, vinRight);        return root;    }};