Merge pull request gzc426#303 from libihan/libihan-patch-1

gzc426 · web-flow · commit 9ef499b3c6e5 · 2018-12-04T17:21:52.000+08:00
Add libh_Binary Tree Level Order Traversal-leetcode102 and 103
diff --git a/2018.12.05-leetcode102/李碧涵.md b/2018.12.05-leetcode102/李碧涵.md
@@ -0,0 +1,40 @@
+### [102. Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal/description/)
+
+**题目描述**
+> 层次遍历二叉树。逐层，从左向右。
+
+**例子**
+略
+
+**思想**
+辅助队列
+
+**解法**
+```python
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def levelOrder(self, root):
+        """
+        :type root: TreeNode
+        :rtype: List[List[int]]
+        """
+        res = []
+        queue = [root]
+        while queue and root:
+            row = []
+            for _ in range(len(queue)):
+                node = queue.pop(0)
+                if node.left:
+                    queue.append(node.left)
+                if node.right:
+                    queue.append(node.right)
+                row.append(node.val)
+            res.append(row)
+        return res
+```
diff --git a/2018.12.06-leetcode103/李碧涵.md b/2018.12.06-leetcode103/李碧涵.md
@@ -0,0 +1,44 @@
+#### [103. Binary Tree Zigzag Level Order Traversal](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/)
+**题目描述**
+> zigzag锯齿形层次遍历二叉树。（逐层，从左向右；然后下一层是从右向左）
+
+**例子**
+略
+
+**思想**
+辅助队列 + Flag翻转标志
+
+**解法**
+```python
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def zigzagLevelOrder(self, root):
+        """
+        :type root: TreeNode
+        :rtype: List[List[int]]
+        """
+        Flag = 1
+        res = []
+        queue = [root]
+        while queue and root:
+            row = []
+            for _ in range(len(queue)):
+                node = queue.pop(0)
+                if node.left:
+                    queue.append(node.left)
+                if node.right:
+                    queue.append(node.right)
+                row.append(node.val)
+            if Flag == 1:
+                res.append(row)
+            else:
+                res.append(row[::-1])
+            Flag *= (-1)
+        return res
+```
