golang力扣leetcode 103. 二叉树的锯齿形层序遍历

103. 二叉树的锯齿形层序遍历

103. 二叉树的锯齿形层序遍历

题解

就是一层翻转一层不翻转，大水题，与前面两篇博文类似

代码

package main

func main() {
    
    

}

type TreeNode struct {
    
    
	Val   int
	Left  *TreeNode
	Right *TreeNode
}
func zigzagLevelOrder(root *TreeNode) [][]int {
    
    
	return levelOrder(root)
}

func reverse(cnt []int) []int {
    
    
	for i, j := 0, len(cnt)-1; i < j; i, j = i+1, j-1 {
    
    
		cnt[i], cnt[j] = cnt[j], cnt[i]
	}
	return cnt
}

func levelOrder(root *TreeNode) [][]int {
    
    
	if root == nil {
    
    
		return nil
	}
	result := make([][]int, 0)
	queue := make([]*TreeNode, 0)

	queue = append(queue, root)
	f:=true
	for len(queue) > 0 {
    
    
		cnt := make([]int, 0)
		queueSize := len(queue)

		for i := 0; i < queueSize; i++ {
    
    
			//出队
			v := queue[0]
			queue = queue[1:]
			//入队
			if v.Left != nil {
    
    
				queue = append(queue, v.Left)
			}
			if v.Right != nil {
    
    
				queue = append(queue, v.Right)
			}

			cnt = append(cnt, v.Val)
		}
		if f{
    
    
			result = append(result, cnt)
			f=false
		} else{
    
    

			result = append(result, reverse(cnt))
			f=true
		}

	}
	return result
}