import java.util.* import kotlin.collections.ArrayList /** * Lock by leetcode * 272. Closest Binary Search Tree Value II * https://www.lintcode.com/problem/closest-binary-search-tree-value-ii/description * https://www.cnblogs.com/grandyang/p/5247398.html * * 当遍历到一个节点时,如果此时结果数组不到k个,我们直接将此节点值加入结果 res 中, * 如果该节点值和目标值的差值的绝对值小于结果 res 的首元素和目标值差值的绝对值,说明当前值更靠近目标值,则将首元素删除,末尾加上当前节点值 */ class TreeNode(var `val`: Int) { var left: TreeNode? = null var right: TreeNode? = null } class Solution { fun closestKValues(root_: TreeNode?, target: Double, k: Int): List<Int> { //inorder val result = ArrayList<Int>(k) var root = root_ val stack = Stack<TreeNode>() while (root != null || stack.isNotEmpty()) { if (root != null) { stack.add(root) root = root.left!! } else { root = stack.pop() if (result.size < k) { result.add(root.`val`) } else if (Math.abs(target - root.`val`) < Math.abs(target - result.get(0))) { result.remove(0) result.add(root.`val`) } root = root.right!! } } return result } }