题目：http://www.nowcoder.com/practice/8a19cbe657394eeaac2f6ea9b0f6fcf6

C++

/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    struct TreeNode* reConstructBinaryTree(vector
     
       pre,vector
      
        in) {        if (pre.size() == 0) {            return NULL;        }        TreeNode *root = new TreeNode(pre[0]);                vector
       
         l_in, r_in, l_pre, r_pre;        bool flag = true;        for (int i = 0; i < pre.size(); i++) {            if (in[i] == pre[0]) {                flag = false;                continue;            }            if (flag == true) {                l_pre.push_back(pre[i+1]);                l_in.push_back(in[i]);            } else {                r_pre.push_back(pre[i]);                r_in.push_back(in[i]);;            }        }                root->left = reConstructBinaryTree(l_pre, l_in);        root->right = reConstructBinaryTree(r_pre, r_in);        return root;    }};