Leetcode/java/110.balanced-binary-tree.java at master · widmonstertony/Leetcode · GitHub

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/*
 * @lc app=leetcode id=110 lang=java
 *
 * [110] Balanced Binary Tree
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public boolean isBalanced(TreeNode root) {
        if (root == null) {
            return true;
        }
        if (isBalanced(root.left) && isBalanced(root.right)) {
            return Math.abs(getHeight(root.left) - getHeight(root.right)) <= 1;
        }
        return false;
    }
    private int getHeight(TreeNode root) {
        if (root == null) {
            return 0;
        }
        return 1 + Math.max(getHeight(root.left), getHeight(root.right));
    }
}
// @lc code=end