题解 | #重建二叉树#

//c++ 递归
/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
#include <cstddef>
#include <vector>
class Solution {
public:
    TreeNode* reConstructBinaryTree(vector<int> pre,vector<int> vin) {
        int m=pre.size();
        int n=vin.size();
        if (m==0||n==0) {
            return NULL;
        }
        TreeNode* root=new TreeNode(pre[0]);
        for(int i=0;i<n;i++){
            if (pre[0]==vin[i]) {
                vector<int> preleft(pre.begin()+1,pre.begin()+i+1);
                vector<int> vinleft(vin.begin(),vin.begin()+i);
                root->left=reConstructBinaryTree(preleft, vinleft);
                vector<int> preright(pre.begin()+i+1,pre.end());
                vector<int> vinright(vin.begin()+i+1,vin.end());
                root->right=reConstructBinaryTree(preright, vinright);
                break;

            }
        }
        return root;


    }
};