LeetCode——Balanced Binary Tree

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

中文：給定一棵二叉樹，檢測其高度上平衡否。

於此題，一棵高度上平衡的二叉樹被定義為一棵每個節點上的兩個子樹上的深度差不能大於1的二叉樹.

遞歸判斷。

Java：

	public boolean isBalanced(TreeNode root) {
		if (root == null)
			return true;
		if (root.left == null && root.right == null)
			return true;
		if (Math.abs(depth(root.left) - depth(root.right)) > 1)
			return false;
		return isBalanced(root.left) && isBalanced(root.right);
	}

	public int depth(TreeNode root) {
		if (root == null)
			return 0;
		return 1 + Math.max(depth(root.left), depth(root.right));
	}