题解 | #重建二叉树#

/**
 * 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* reConstructBinaryTree(vector<int> pre,vector<int> vin) {
        if(vin.size()==0)
        {
            return NULL;
        }
        TreeNode *head=new TreeNode(pre[0]);
        vector<int> pre_r,pre_l,vin_r,vin_l;
        int t=0;
        while(vin[t]!=pre[0])
        {
            t++;
        }
        for(int i=0;i<t;i++)
        {
            pre_l.push_back(pre[i+1]);
            vin_l.push_back(vin[i]);
        }
        for(int i=t+1;i<vin.size();i++)
        {
            pre_r.push_back(pre[i]);
            vin_r.push_back(vin[i]);
        }
        head->right=reConstructBinaryTree(pre_r,vin_r);
        head->left=reConstructBinaryTree(pre_l,vin_l);
        return head;
    }
};