leetcode 面试题 04.04. 检查平衡性

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
public boolean isBalanced(TreeNode root) {
    return find(root) >= 0;
}

private int find(TreeNode node) {
    if (node == null) {
        return 0;
    }
    int l = find(node.left);
    if (l < 0) {
        return l;
    }
    int r = find(node.right);
    if (r < 0) {
        return r;
    }
    if (Math.abs(l - r) > 1) {
        return -1;
    }
    return Math.max(l, r) + 1;
}
}