每日一题---剑指 Offer 32 - III. 从上到下打印二叉树 III[力扣][Go]

// 利用顺序表做，不递归
func levelOrder(root *TreeNode) [][]int {
    var sum [][]int
    var tem []int
    n := 1
    var queue []*TreeNode
    if root != nil {
        queue = append(queue, root)
    }
    for len(queue) != 0 {
        if n%2 == 0{
            for size := len(queue) - 1; size >= 0; size-- {
                node := queue[size]
                tem = append(tem, node.Val)
                if node.Right != nil {
                    queue = append(queue, node.Right)
                }
                if node.Left != nil {
                    queue = append(queue, node.Left)
                }
                if size == 0{
                    queue = queue[1:]
                } else {
                    tem2 := queue[size+1:]
                    queue = queue[:size]
                    for _, treeNode := range tem2 {
                        queue = append(queue,treeNode)
                    }
                }
            }
        } else {
            for size := len(queue) - 1; size >= 0; size-- {
                node := queue[size]
                tem = append(tem, node.Val)
                if node.Left != nil {
                    queue = append(queue, node.Left)
                }
                if node.Right != nil {
                    queue = append(queue, node.Right)
                }
                if size == 0{
                    queue = queue[1:]
                } else {
                    tem2 := queue[size+1:]
                    queue = queue[:size]
                    for _, treeNode := range tem2 {
                        queue = append(queue,treeNode)
                    }
                }
            }
        }
        sum = append(sum, tem)
        tem = []int{}
        n++
    }
    return sum
}