剑指 Offer 55

class Solution(object):
    def isBalanced(self, root):
        """
        :type root: TreeNode
        :rtype: bool
        """
        if not root:
            return True
        # 求左子树深度
        leftDenth = self.treeDepth(root.left)
        rightDenth = self.treeDepth(root.right)
        resLeft = self.isBalanced(root.left)
        resRight = self.isBalanced(root.right)
        if resLeft and resRight and abs(leftDenth-rightDenth)<=1:
            return True
        else:
            return False

    # 求二叉树的深度
    def treeDepth(self, root):
        if not root:
            return 0
        depthLeft = self.treeDepth(root.left)
        depthRight = self.treeDepth(root.right)
        return depthLeft + 1 if depthLeft > depthRight else depthRight + 1