[leetcode] Construct Binary Tree from Preorder and Inorder Traversal

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

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

class Solution {
public:
    TreeNode *buildTree(vector<int> &preorder, vector<int> &inorder) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(inorder.size()==0)
            return NULL;
        TreeNode *root=Build(0,preorder.size()-1,0,inorder.size()-1,preorder,inorder);
        return root;
    }
    TreeNode *Build(int lp,int rp,int li,int ri,vector<int> &preorder , vector<int> &inorder){
        if(lp>rp || lp>preorder.size()-1)
            return NULL;
        TreeNode *root=new TreeNode(preorder[lp]);
        TreeNode *left,*right;
        int i;
        for(i=li;i<=ri;i++)
            if(inorder[i]==preorder[lp])
                break;
        int lt=i-li;
        int rt=ri-i;
        left=Build(lp+1,lp+lt,li,i-1,preorder,inorder);
        right=Build(lp+1+lt,rp,i+1,ri,preorder,inorder);
        root->left=left;
        root->right=right;
        return root;
    }
};