public class Solution {
    // 求深度
    public int TreeDepth(TreeNode root) {
        return root == null ? 0 : Math.max(TreeDepth(root.left)+1, TreeDepth(root.right)+1);
    }
    public boolean IsBalanced_Solution(TreeNode root) {
        if(root == null)
            return true;
        
        int left = TreeDepth(root.left);
        int right = TreeDepth(root.right);
        return Math.abs(left - right) > 1 ? false : true && IsBalanced_Solution(root.left) && IsBalanced_Solution(root.right);
    }
}