問題形貌

從上往下打印出二叉樹的每一個節點，同層節點從左至右打印。

剖析

二叉樹的條理遍歷，能夠藉助行列的協助

完成

/* function TreeNode(x) {
    this.val = x;
    this.left = null;
    this.right = null;
} */
function PrintFromTopToBottom(r)
{
    if(r === null)
        return [];
    var q = [];
    var res = [];
    q.push(r);
    while(q.length !== 0){
        var cur = q.shift();
        res.push(cur.val);
        if(cur.left)
            q.push(cur.left);
        if(cur.right)
            q.push(cur.right);
    }
    
    return res;
}