/* function TreeNode(x) {
    this.val = x;
    this.left = null;
    this.right = null;
} */
function PrintFromTopToBottom(root)
{
    // write code here
    var queue = [];//隊(duì)列
    queue.push(root);
    var result = [];//存放打印結(jié)果
    
    if(root == null){
        return result;
    }
    
while(queue.length){//只要沒遍歷完，就一直會(huì)每次運(yùn)行完下面代碼隊(duì)列都不為空
//注意這里寫法，不能直接寫為queue，必須是它的長(zhǎng)度不為0
        var temp = queue.shift();//最先的那個(gè)數(shù)出隊(duì)列
        result.push(temp.val);//將出隊(duì)列的這個(gè)數(shù)的數(shù)值push到結(jié)果中
        if(temp.left){
            queue.push(temp.left);
        }
        if(temp.right){
            queue.push(temp.right);
        }
    }
    return result;
}