题解 | #求二叉树的层序遍历#

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

/**
  * 
  * @param root TreeNode类 
  * @return int整型二维数组
*/
func levelOrder( root *TreeNode ) [][]int {
    // write code here
	res := make([][]int, 0)
    if root == nil {
        return nil
    }
	level := make([]*TreeNode, 0)
	level = append(level, root)
	for len(level) != 0 {
		size := len(level)
		tmpNode := make([]*TreeNode, 0)
		tmp := make([]int, 0)
		for index := 0; index < size; index++ {
			currentNode := level[0]
			level = level[1:]
			tmp = append(tmp, currentNode.Val)
			if currentNode.Left != nil {
				tmpNode = append(tmpNode, currentNode.Left)
			}
			if currentNode.Right != nil {
				tmpNode = append(tmpNode, currentNode.Right)
			}
		}
		level = append(level, tmpNode...)
		res = append(res, tmp)
	}
	return res
}