From bfc7e3ffc08d18ac018297976923b4f29ba4115c Mon Sep 17 00:00:00 2001
From: YDZ <ydz627@gmail.com>
Date: Sat, 22 Jun 2019 22:23:44 +0800
Subject: [PATCH] =?UTF-8?q?=E6=9B=B4=E6=96=B0=20problems=20102?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../102. Binary Tree Level Order Traversal.go | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/Algorithms/0102. Binary Tree Level Order Traversal/102. Binary Tree Level Order Traversal.go b/Algorithms/0102. Binary Tree Level Order Traversal/102. Binary Tree Level Order Traversal.go
index e3ea8c87..caf5fca2 100644
--- a/Algorithms/0102. Binary Tree Level Order Traversal/102. Binary Tree Level Order Traversal.go	
+++ b/Algorithms/0102. Binary Tree Level Order Traversal/102. Binary Tree Level Order Traversal.go	
@@ -8,6 +8,8 @@ package leetcode
  *     Right *TreeNode
  * }
  */
+
+// 解法一 BFS
 func levelOrder(root *TreeNode) [][]int {
 	if root == nil {
 		return [][]int{}
@@ -39,3 +41,23 @@ func levelOrder(root *TreeNode) [][]int {
 	}
 	return res
 }
+
+// 解法二 DFS
+func levelOrder_(root *TreeNode) [][]int {
+	levels := [][]int{}
+	dfsLevel(root, -1, &levels)
+	return levels
+}
+
+func dfsLevel(node *TreeNode, level int, res *[][]int) {
+	if node == nil {
+		return
+	}
+	currLevel := level + 1
+	for len(*res) <= currLevel {
+		*res = append(*res, []int{})
+	}
+	(*res)[currLevel] = append((*res)[currLevel], node.Val)
+	dfsLevel(node.Left, currLevel, res)
+	dfsLevel(node.Right, currLevel, res)
+}