added python for 003.

Author: pezy

003. Same Tree/README.md

@@ -1,4 +1,12 @@
+# 思路(C++)
+
 这道题没啥好说的，太简单了，尤其是刚做过昨天那道。我几乎直接在LeetCode上写下了答案，连本地编译都没用，抱着试试运气的心态，竟直接AC了。
 花了不到3分钟。
 
 递归还是那个递归，门口有一颗二叉树，另一颗也是二叉树。它们长得一样不？从根开始看呗。好无聊。
+
+## Python
+
+值得注意的是，Python 里更习惯用 `is` 来比较，如果只是判断非零（有效）时，可以直接用 `if p:` 这样更简洁的方式。
+
+参考：<https://stackoverflow.com/questions/7816363/if-a-vs-if-a-is-not-none>

003. Same Tree/solution.py

@@ -0,0 +1,41 @@
+#!python3
+
+
+class TreeNode:
+    def __init__(self, x):
+        self.val = x
+        self.left = None
+        self.right = None
+
+
+class Solution:
+    def isSameTree(self, p, q):
+        """
+        :type p: TreeNode
+        :type q: TreeNode
+        :rtype: bool
+        """
+        if p and q:
+            return p.val == q.val and self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)
+        return p is q
+
+
+if __name__ == "__main__":
+    example1 = TreeNode(1)
+    example1.left = TreeNode(2)
+    example1.right = TreeNode(3)
+    assert(Solution().isSameTree(example1, example1) is True)
+
+    example2l = TreeNode(1)
+    example2l.left = TreeNode(2)
+    example2r = TreeNode(1)
+    example2r.right = TreeNode(2)
+    assert(Solution().isSameTree(example2l, example2r) is False)
+
+    example3l = TreeNode(1)
+    example3l.left = TreeNode(2)
+    example3l.right = TreeNode(1)
+    example3r = TreeNode(1)
+    example3r.left = TreeNode(1)
+    example3r.right = TreeNode(2)
+    assert(Solution().isSameTree(example3l, example3r) is False)

README.md

@@ -7,7 +7,7 @@ LeetCode solutions in C++ 11. (From Easy to Hard)
 |---|-----|--------|--------|----------|
 |1|[Single Number][1]|[C++](001.%20Single%20Number/solution.h)|[Python](001.%20Single%20Number/solution.py)|2014/10/15|Medium|
 |2|[Maximum Depth of Binary Tree][2]|[C++](002.%20Maximum%20Depth%20of%20Binary%20Tree/solution.h)|[Python](002.%20Maximum%20Depth%20of%20Binary%20Tree/solution.py)|2014/10/16|Easy|
-|3|[Same Tree][3]|[C++](003.%20Same%20Tree/solution.h)|2014/10/17|Easy|
+|3|[Same Tree][3]|[C++](003.%20Same%20Tree/solution.h)|[Python](003.%20Same%20Tree/solution.py)|2014/10/17|Easy|
 |4|[Reverse Integer][4]|[C++](004.%20Reverse%20Integer/solution.h)|2014/10/18|Easy|
 |5|[Best Time to Buy and Sell Stock II][5]|[C++](005.%20Best%20Time%20to%20Buy%20and%20Sell%20Stock%20II/solution.h)|2014/10/19|Medium|
 |6|[Unique Binary Search Trees][6]|[C++](006.%20Unique%20Binary%20Search%20Trees/solution.h)|2014/10/20|Medium|