题解 | #按之字形顺序打印二叉树#

import . "nc_tools"
/*
 * type TreeNode struct {
 *   Val int
 *   Left *TreeNode
 *   Right *TreeNode
 * }
 */

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 * 
 * @param pRoot TreeNode类 
 * @return int整型二维数组
*/
//BFS+队列
func Print( root *TreeNode ) [][]int {
    // write code here
    res := [][]int{}
    if root == nil {return nil}
    queue := []*TreeNode{root}
    for len(queue) > 0 {
        n := len(queue)
        tmp := make([]int, n)
        for i := 0; i < n; i++ {
            if queue[i] == nil {
                continue
            }
            if len(res)%2 == 0 {
                tmp[i] = queue[i].Val
            }else {
                tmp[n-1-i] = queue[i].Val
            }
            if queue[i].Left != nil {
                queue = append(queue, queue[i].Left)
            }
            if queue[i].Right != nil  {
                queue = append(queue, queue[i].Right)
            }
        }
        queue = queue[n:]
        res = append(res, tmp)
    }
    return res
}