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
/** * 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 == NULL){ return NULL; } if (root -> val < L){ root -> left = NULL; return trimBST(root -> right, L, R); } else if (root -> val > R){ root -> right = NULL; return trimBST(root -> left, L, R); } else{ root -> left = trimBST(root -> left, L, R); root -> right = trimBST(root -> right, L, R); } return root; } };
Leetcode 669. Trim a Binary Search Tree
原文：http://www.cnblogs.com/simplepaul/p/7679092.html