binary-tree-right-side-view.go

// https://leetcode.com/problems/binary-tree-right-side-view

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */

type LevelNode struct {
    node *TreeNode
    level int
}

func rightSideView(root *TreeNode) []int {
    if root == nil {
        return []int{}
    }
    
    result := []int{}
    queue := []*LevelNode{
        &LevelNode{node: root, level: 1},
    }
    
    for len(queue) > 0 {
        curr := queue[0]
        queue = queue[1:]
        
        if len(result) < curr.level {
            result = append(result, curr.node.Val)
        }
        
        if curr.node.Right != nil {
            queue = append(queue, &LevelNode{
                node: curr.node.Right,
                level: curr.level + 1,
            })
        }
        
        if curr.node.Left != nil {
            queue = append(queue, &LevelNode{
                node: curr.node.Left,
                level: curr.level + 1,
            })
        }
    }
    
    return result
}