[leetcode] Construct Binary Tree from Inorder and Postorder Traversal

From : https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/

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

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

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    TreeNode* buildTree(vector<int>& inorder, vector<int>& postorder) {        return build(inorder, postorder, 0, inorder.size()-1, 0, postorder.size()-1);    }    TreeNode* build(vector<int>& in, vector<int>& post, int si, int ei, int sp, int ep) {        if(si>ei || sp>ep) return NULL;        if(si==ei) return new TreeNode(in[si]);        int rv=post[ep], inIdx=si;        while(in[inIdx]!=rv) inIdx++;        int postIdx=ep-ei+inIdx;        TreeNode *root = new TreeNode(rv);        root->left = build(in, post, si, inIdx-1, sp, postIdx-1);        root->right = build(in, post, inIdx+1, ei, postIdx, ep-1);        return root;    }};