669. Trim a Binary Search Tree
Medium
Given the
root of a binary search tree and the lowest and highest boundaries as low and high, trim the tree so that all its elements lies in [low, high]. Trimming the tree should not change the relative structure of the elements that will remain in the tree (i.e., any node's descendant should remain a descendant). It can be proven that there is a unique answer.Return the root of the trimmed binary search tree. Note that the root may change depending on the given bounds.
Example 1:
Input: root = [1,0,2], low = 1, high = 2
Output: [1,null,2]
Example 2:
Input: root = [3,0,4,null,2,null,null,1], low = 1, high = 3
Output: [3,2,null,1]
Constraints:
- The number of nodes in the tree is in the range
[1, 10^4]. 0 <= Node.val <= 10^4- The value of each node in the tree is unique.
rootis guaranteed to be a valid binary search tree.0 <= low <= high <= 10^4
Runtime: 6 ms, faster than 100%
Memory Usage: 6.4 MB, less than 100%
/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func trimBST(root *TreeNode, low int, high int) *TreeNode {
if root == nil { return nil }
if root.Val < low {
return trimBST(root.Right, low, high)
} else if root.Val > high {
return trimBST(root.Left, low, high)
}
return &TreeNode{ Val: root.Val, Left: trimBST(root.Left, low, high), Right: trimBST(root.Right, low, high) }
}
Last modified 5mo ago