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 ) {
    let arr = []
    function traversal(root, arr, level) {
        if(root === null) return
        if(arr[level] === undefined) arr[level] = []
        arr[level].push(root.val)
        traversal(root.left, arr, level+1)
        traversal(root.right, arr, level+1)
    }
    traversal(root, arr, 0)
    return arr
}
module.exports = {
    levelOrder : levelOrder
};