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
A:
递归啊,没别的方法
/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode() : val(0), left(nullptr), right(nullptr) {} * TreeNode(int x) : val(x), left(nullptr), right(nullptr) {} * TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {} * }; */ class Solution { public: TreeNode* trimBST(TreeNode* root, int L, int R) { if(root == nullptr) return root; if(root->val <L) return trimBST(root->right, L, R); else if(root->val >R) return trimBST(root->left, L, R); root->left = trimBST(root->left, L, R); root->right = trimBST(root->right, L, R); return root; } };
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