Check Balanced

Author: anantkaushik

Trees-and-Graphs/check-balanced.py

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+"""
+Implement a function to check if a binary tree is balanced. For the purposes of this question, a balanced tree is defined
+to be a tree such that the heights of the two subtrees of any node never differ by more than one.
+"""
+class Solution(object):
+    def isBalanced(self, root):
+        def check(root):
+            if root is None:
+                return 0
+            left  = check(root.left)
+            right = check(root.right)
+            if left == -1 or right == -1 or abs(left - right) > 1:
+                return -1
+            return 1 + max(left, right)
+        return check(root) != -1