题解 | #求二叉树的层序遍历#

/*
 * function TreeNode(x) {
 *   this.val = x;
 *   this.left = null;
 *   this.right = null;
 * }
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 *
 * @param root TreeNode类
 * @return int整型二维数组
 */
function levelOrder(root) {
    // write code here

    const result = [];
    const traverse = (node, layer) => {
        if (node !== null) {
            traverse(node.left, layer + 1);
            result[layer]
                ? result[layer].push(node.val)
                : (result[layer] = [node.val]);
            traverse(node.right, layer + 1);
        }
    };

    traverse(root, 0);
    return result;
}
module.exports = {
    levelOrder: levelOrder,
};