每天一道剑指offer-平衡二叉树

public class Solution {
    private boolean flag = true;
    public boolean IsBalanced_Solution(TreeNode root) {
        TreeLength(root);
        return flag;
    }
    private int TreeLength(TreeNode root)
    {
        if(root == null)
            return 0;
        int left = TreeLength(root.left);//左子树的高度
        int right = TreeLength(root.right);//右子树的高度
        if(left-right >= 2 || right - left >= 2)
        {//左右子树高度差大于等于2，标记就不是true
            flag = false;
        }
        return left>right?(left+1):(right+1);
    }
}