/**

?*?1.?題目非常簡(jiǎn)單，剛開始還想著有沒有什么更好的方法。不過很快就覺得遞歸就是最快的。10分鐘就寫好了，一次通過。

?*?2.?1ms,擊敗99.76%；?40MB，擊敗27.34%；

?*?

?*/

class?Solution?{

????public?boolean?isBalanced(TreeNode?root)?{

????????if(isBalancedHelp(root)?<?0){

????????????return?false;

????????}

????????return?true;

????}

????public?int?isBalancedHelp(TreeNode?root){

????????if(root?==?null){

????????????return?0;

????????}

????????int?leftNumber?=?isBalancedHelp(root.left);

????????int?rightNumber?=?isBalancedHelp(root.right);

????????if(leftNumber?<?0?||?rightNumber?<?0){

????????????return?-1;

????????}

????????if(Math.abs(leftNumber-rightNumber)>1){

????????????return?-1;

????????}

????????return?Math.max(leftNumber?+?1,?rightNumber+1);

????}

}