/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func levelOrder(root *TreeNode) [][]int {
if root == nil {
return nil
}
res := make([][]int, 0)
queue := []*TreeNode{root}
for len(queue) > 0 {
tmpArr := make([]*TreeNode, 0)
tmpRes := make([]int, len(queue))
for idx, node := range queue {
tmpRes[idx] = node.Val
if node.Left != nil {
tmpArr = append(tmpArr, node.Left)
}
if node.Right != nil {
tmpArr = append(tmpArr, node.Right)
}
}
res = append(res, tmpRes)
queue = tmpArr
}
return res
}