题解 | #判断是不是平衡二叉树#

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 *   public TreeNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param pRoot TreeNode类
     * @return bool布尔型
     */
    public boolean IsBalanced_Solution (TreeNode pRoot) {
        // write code here
        if(pRoot == null) {
            return true;
        }  
        int left = 0;
        // 获取左子树高度
        if (pRoot.left != null) {
            left = getSolution(pRoot.left);
        }
        // 获取右子树高度
        int right = 0;
        if (pRoot.right != null) {
            right = getSolution(pRoot.right);
        }
        if (Math.abs(left - right) > 1 ) {
            return false;
        } else {
            return IsBalanced_Solution(pRoot.left) && IsBalanced_Solution(pRoot.right);
        }
    }

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