110. Balanced Binary Tree Java Solutions

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.

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/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public boolean isBalanced(TreeNode root) {
        return height(root) != -1;
    }
    
    public int height(TreeNode t){
        if(t == null) return 0; //到叶子节点再往下的情况
        int lheight = height(t.left);
        int rheight = height(t.right);
        if(lheight == -1 || rheight == -1 || Math.abs(lheight-rheight) > 1){
            return -1;//使用-1 标记左右子树高度相差大于1的情况
        }
        return 1 + Math.max(lheight,rheight);
    }
}