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| // @Title: 二叉树的前序遍历 (Binary Tree Preorder Traversal)
// @Author: 15816537946@163.com
// @Date: 2019-11-25 18:17:16
// @Runtime: 0 ms
// @Memory: 2.1 MB
/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
/*
func preorderTraversal(root *TreeNode) []int {
if root == nil {
return nil
}
res := make([]int,0)
var dfs func(*TreeNode)
dfs = func(node *TreeNode) {
if node == nil {
return
}
res = append(res, node.Val)
dfs(node.Left)
dfs(node.Right)
}
dfs(root)
return res
}
*/
func preorderTraversal(root *TreeNode) []int {
if root == nil {
return nil
}
res := make([]int, 0)
nodes := make([]*TreeNode, 1, 1024)
nodes[0] = root
for len(nodes) > 0 {
node := nodes[0]
nodes = nodes[1:]
res = append(res, node.Val)
if node.Right != nil {
nodes = append(nodes, node.Right)
}
if node.Left != nil {
nodes = append(nodes, node.Left)
}
}
return res
}
/*
func preorderTraversal(root *TreeNode) []int {
if root == nil {
return nil
}
res := make([]int, 0)
nodes := make([]*TreeNode, 1, 1024)
nodes[0] = root
for len(nodes) > 0 {
node := nodes[len(nodes)-1]
nodes = nodes[:len(nodes)-1]
res = append(res, node.Val)
if node.Right != nil {
nodes = append(nodes, node.Right)
}
if node.Left != nil {
nodes = append(nodes, node.Left)
}
}
return res
}
*/
|