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| // @Title: 二叉树的锯齿形层序遍历 (Binary Tree Zigzag Level Order Traversal)
// @Author: 15816537946@163.com
// @Date: 2020-12-22 23:55:08
// @Runtime: 0 ms
// @Memory: 2.9 MB
/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func zigzagLevelOrder(root *TreeNode) [][]int {
res := [][]int{}
var dfs func(*TreeNode, int)
dfs = func(node *TreeNode, level int) {
if node == nil {
return
}
if level >= len(res) {
res = append(res, []int{})
}
if level%2 == 0 {
res[level] = append(res[level], node.Val)
} else {
// 翻转列表
tmp := make([]int, len(res[level])+1)
tmp[0] = node.Val
copy(tmp[1:], res[level])
res[level] = tmp
}
dfs(node.Left, level+1)
dfs(node.Right, level+1)
}
dfs(root, 0)
return res
}
|