4 重建二叉樹
阿新 • • 發佈:2018-11-22
/**
* 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) {
int len = pre.size();
if(len == 0) return NULL;
int idx;
for(int i = 0; i < len; ++i){
if(vin[i] == pre[0]){
idx = i;
break;
}
}
vector<int> pre_left, pre_right, vin_left, vin_right;
for(int i = 0 ; i< idx; ++i){
pre_left.push_back(pre[i+1]);
vin_left.push_back(vin[i]);
}
for(int i = idx + 1; i < len; ++i){
pre_right.push_back(pre[i]);
vin_right.push_back(vin[i]);
}
TreeNode* head = new TreeNode(pre[0]);
head->left = reConstructBinaryTree(pre_left, vin_left);
head->right = reConstructBinaryTree(pre_right, vin_right);
return head;
}
};