LeetCode in Kotlin
199. Binary Tree Right Side View
Medium
Given the root of a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.
Example 1:
Input: root = [1,2,3,null,5,null,4]
Output: [1,3,4]
Example 2:
Input: root = [1,null,3]
Output: [1,3]
Example 3:
Input: root = []
Output: []
Constraints:
- The number of nodes in the tree is in the range
[0, 100]. -100 <= Node.val <= 100
Solution
import com_github_leetcode.TreeNode
/*
* Example:
* var ti = TreeNode(5)
* var v = ti.`val`
* Definition for a binary tree node.
* class TreeNode(var `val`: Int) {
* var left: TreeNode? = null
* var right: TreeNode? = null
* }
*/
class Solution {
fun rightSideView(root: TreeNode?): List<Int> {
val list: MutableList<Int> = ArrayList()
recurse(root, 0, list)
return list
}
private fun recurse(node: TreeNode?, level: Int, list: MutableList<Int>) {
if (node != null) {
if (list.size < level + 1) {
list.add(node.`val`)
}
recurse(node.right, level + 1, list)
recurse(node.left, level + 1, list)
}
}
}