剑指offer面试题[6]-重建二叉树

题目描述

输入某二叉树的前序遍历和中序遍历的结果，请重建出该二叉树。假设输入的前序遍历和中序遍历的结果中都不含重复的数字。例如输入前序遍历序列{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6}，则重建二叉树并返回。

/** * 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) {         if(pre.empty()||vin.empty())             return NULL;         TreeNode*  root=reConstructCore(pre,vin);         return root;    }        TreeNode* reConstructCore(vector<int> pre,vector<int> vin) {         if(pre.empty())             return NULL;         vector<int> preLeft,preRight,vinLeft,vinRight;         int rootValue=pre[0];         TreeNode* root=new TreeNode(rootValue);         int len=pre.size();         int index=0;         for(int i=0;i<len;i++)           {               if(vin[i]==rootValue)                 {                     index=i;                     break;                 }           }        for(int j=0;j<index;j++)           {               preLeft.push_back(pre[j+1]);               vinLeft.push_back(vin[j]);           }        for(int j=index+1;j<len;j++)           {               preRight.push_back(pre[j]);               vinRight.push_back(vin[j]);                           }        root->left=reConstructCore(preLeft,vinLeft);        root->right=reConstructCore(preRight,vinRight);           return root;    }};