Title
Given a binary search tree and the lowest and highest boundaries as L and R, trim the tree so that all its elements lies in [L, R] (R >= L). You might need to change the root of the tree, so the result should return the new root of the trimmed binary search tree.
Example 1:
Input:
1
/ \
0 2
L = 1
R = 2
Output:
1
\
2
Example 2:
Input:
3
/ \
0 4
\
2
/
1
L = 1
R = 3
Output:
3
/
2
/
1
这个思想挺重要的撒！！！
题目大意：要指定区间的树
Solution
//cpp:
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
TreeNode* trimBST(TreeNode* root, int L, int R) {
if(!root)
return NULL;
if(root->val>R)
return trimBST(root->left,L,R);
if(root->val<L)
return trimBST(root->right,L,R);
root->left=trimBST(root->left,L,R);
root->right=trimBST(root->right,L,R);
return root;
}
};