剑指OFFER----重建二叉树

题目描述

/**
* 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()||pre.size()!=vin.size())return NULL;
return CreateTree(pre.begin(),vin.begin(),pre.size());
}
TreeNode *CreateTree(vector<int>::iterator itp,vector<int>::iterator itv,int n )
{
if ( n <= 0 )return NULL;
TreeNode *root = new TreeNode(*itp);
int index = FindV(itv,*itp,n);
if(index == -1)exit(-1);
root->left = CreateTree(itp + 1, itv, index);
root->right = CreateTree(itp + index + 1, itv + index + 1, n - index -1);
return root;
}
int FindV(vector<int>::iterator it,int val,int n)
{
for(int i = 0; i < n ; ++i,++it)
if( *it == val)return i;
return -1;
}
};