add most-frequent-subtree-sum[1].py

Author: lightmen

python/hash-table/most-frequent-subtree-sum[1].py

@@ -0,0 +1,30 @@
+# 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 __init__(self):
+        self.c = collections.Counter()
+
+    def depth(self, root):
+        if not root:
+            return 0
+        left = self.depth(root.left)
+        right = self.depth(root.right)
+
+        total = root.val + left + right
+        self.c[total] += 1
+        return total
+
+    def findFrequentTreeSum(self, root):
+        """
+        :type root: TreeNode
+        :rtype: List[int]
+        """
+        self.depth(root)
+        maxfreq = max(self.c.values() + [None])
+
+        return [k for k, v in self.c.items() if v == maxfreq]