【剑指offer】22 从上往下打印二叉树

 1 function PrintFromTopToBottom(root)
 2 {
 3     // write code here
 4     var arr = [];
 5     if(!root) return arr;
 6     var tree = [];
 7     tree.push(root);
 8     while(tree.length){
 9         var rt = tree[0];
10         if(rt.left) tree.push(rt.left);
11         if(rt.right) tree.push(rt.right);
12         arr.push(tree.shift().val);
13     }
14     return arr;
15 }