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.

/** * 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 *buildTree(vector<int> &preorder, vector<int> &inorder) {return creatTree(preorder, 0, preorder.size() - 1, inorder, 0, inorder.size() - 1);}TreeNode *creatTree(vector<int> &preorder, int pL, int pR,vector<int> &inorder, int iL, int iR) {if (pL > pR)return NULL;if (pL == pR)return new TreeNode(preorder[pL]);TreeNode *head = new TreeNode(preorder[pL]);int mid = iL;while (mid <= iR && inorder[mid] != preorder[pL])mid++;head->left = creatTree(preorder, pL + 1, pL + mid - iL, inorder, iL, mid - 1);head->right = creatTree(preorder, pL + mid - iL + 1, pR, inorder, mid + 1, iR);return head;}};