[Leetcode] construct-binary-tree-from-preorder-and-inorder-, preorderinorder

[Leetcode] construct-binary-tree-from-preorder-and-inorder-, preorderinorder
Description

 

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

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

/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:            void ConstructTree(TreeNode *&tree, vector<int> &preorder, int prebegin, int preend, vector<int> &inorder, int inbegin, int inend)    {        if(prebegin > preend || inbegin > inend)            return;        int i;        int mid = preorder[prebegin];        for(i = inbegin; i <= inend; i++)        {            if(inorder[i] == mid)                break;        }        tree = new TreeNode(mid);        ConstructTree(tree->left, preorder, prebegin+1, prebegin+i-inbegin, inorder, inbegin, i-1);        ConstructTree(tree->right, preorder, prebegin+i+1-inbegin, preend, inorder, i+1, inend);    }            TreeNode *buildTree(vector<int> &preorder, vector<int> &inorder)     {        if(preorder.size() == 0 || inorder.size() == 0)            return NULL;        TreeNode *tree = NULL;                ConstructTree(tree, preorder, 0, preorder.size()-1, inorder, 0, inorder.size()-1);                return tree;    }};