From b0f60073c8b1c64612fe6445358b4eeaf112394d Mon Sep 17 00:00:00 2001
From: gbabyX <showphp@foxmail.com>
Date: Thu, 12 Nov 2020 10:26:25 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BA=8C=E5=8F=89=E6=A0=91=E7=9A=84=E5=89=8D?=
 =?UTF-8?q?=E5=BA=8F=E9=81=8D=E5=8E=86?=
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---
 202011/btree/pre.go  | 21 +++++++++++++++++++++
 202011/btree/tree.go |  7 +++++++
 2 files changed, 28 insertions(+)
 create mode 100644 202011/btree/pre.go
 create mode 100644 202011/btree/tree.go

diff --git a/202011/btree/pre.go b/202011/btree/pre.go
new file mode 100644
index 0000000..fbc66a8
--- /dev/null
+++ b/202011/btree/pre.go
@@ -0,0 +1,21 @@
+package btree
+
+func preorderTraversal(root *TreeNode) []int {
+	if root == nil {
+		return nil
+	}
+	var l []int
+	preoder(root, &l)
+	return l
+}
+
+func preoder(node *TreeNode, l *[]int) {
+	v := node.Val
+	*l = append(*l, v)
+	if node.Left != nil {
+		preoder(node.Left, l)
+	}
+	if node.Right != nil {
+		preoder(node.Right, l)
+	}
+}
diff --git a/202011/btree/tree.go b/202011/btree/tree.go
new file mode 100644
index 0000000..5c43721
--- /dev/null
+++ b/202011/btree/tree.go
@@ -0,0 +1,7 @@
+package btree
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}