判断一棵树是不是二叉平衡树

转载代码：

public class Solution {
    private boolean isBalanced = false;//最后的返回值
    public boolean IsBalanced_Solution(TreeNode root) {
        getDepth(root);
        return isBalanced;
    }
    public int getDepth(TreeNode root) {
        if(root == null) {
            isBalanced = true;
            return 0;
        }
        int left = getDepth(root.left);//递归左子树
        int right = getDepth(root.right);//递归右子树
        int depth = (left > right ? left : right) + 1;
        if(Math.abs(left - right) <= 1) {
            isBalanced = true;
        } else {
            isBalanced = false;
        }
        return depth;
    }
}