199-binary-tree-right-side-view.go

package main

func rightSideView(root *TreeNode) []int {
	if root == nil {
		return []int{}
	}
	res := make([]int, 0)
	queue := make([]*TreeNode, 0)
	queue = append(queue, root)
	for len(queue) > 0 {
		sz := len(queue)
		var last *TreeNode
		for i := 0; i < sz; i++ {
			cur := queue[0]
			last = cur
			queue = queue[1:]
			if cur.Left != nil {
				queue = append(queue, cur.Left)
			}
			if cur.Right != nil {
				queue = append(queue, cur.Right)
			}
		}
		res = append(res, last.Val)
	}
	return res
}