Add solution 0589

leetcode/0589.N-ary-Tree-Preorder-Traversal/589. N-ary Tree Preorder Traversal.go

@@ -0,0 +1,43 @@
+package leetcode
+
+//  Definition for a Node.
+type Node struct {
+	Val      int
+	Children []*Node
+}
+
+// 解法一 非递归
+func preorder(root *Node) []int {
+	res := []int{}
+	if root == nil {
+		return res
+	}
+	stack := []*Node{root}
+	for len(stack) > 0 {
+		r := stack[len(stack)-1]
+		stack = stack[:len(stack)-1]
+		res = append(res, r.Val)
+		tmp := []*Node{}
+		for _, v := range r.Children {
+			tmp = append([]*Node{v}, tmp...) // 逆序存点
+		}
+		stack = append(stack, tmp...)
+	}
+	return res
+}
+
+// 解法二 递归
+func preorder1(root *Node) []int {
+	res := []int{}
+	preorderdfs(root, &res)
+	return res
+}
+
+func preorderdfs(root *Node, res *[]int) {
+	if root != nil {
+		*res = append(*res, root.Val)
+		for i := 0; i < len(root.Children); i++ {
+			preorderdfs(root.Children[i], res)
+		}
+	}
+}