[leetcode]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 binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    int findInVector(vector<int> vec, int val){          for(int i = 0; i < vec.size(); i++){              if(vec[i] == val) return i;          }                    return -1;      }        TreeNode *build(int is, int ps, int N, vector<int> &inorder, vector<int> &postorder){          if(N == 0) return NULL;          int rootvalue = postorder[ps+N-1];          TreeNode *root = new TreeNode(rootvalue);                    if(N == 1) return root;          int in_index = findInVector(inorder, rootvalue);                    int left_len = in_index - is;          int right_len = N - 1 - left_len;                    root -> left = build(is, ps, left_len, inorder, postorder);          root -> right = build(is+1+left_len, ps+left_len, right_len, inorder, postorder);                    return root;        }           TreeNode *buildTree(vector<int> &inorder, vector<int> &postorder) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        return build(0, 0, inorder.size(), inorder, postorder);     }};