题解 | #求二叉树的层序遍历#

 * function TreeNode(x) {
 *   this.val = x;
 *   this.left = null;
 *   this.right = null;
 * }
 */

/**
  * 
  * @param root TreeNode类 
  * @return int整型二维数组
  */
function levelOrder( root ) {
    // write code here
    if(!root) return [];
    let queue = [root];
    let res = [];
    
    while(queue.length) {
        let level = [];
        let size = queue.length;
        
        while(size--) {
            let cur = queue.shift();
            level.push(cur.val);
            if(cur.left) queue.push(cur.left);
            if(cur.right) queue.push(cur.right);
        }
        res.push(level);
    }
    return res;
}
module.exports = {
    levelOrder : levelOrder
};