题解 | #牛群中最受欢迎的牛#

/**
 * 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 nums int整型一维数组
 * @param k int整型
 * @return int整型一维数组
 */
function most_popular_cows(nums, k) {
  // write code here
  let obj = {};
  for (let n of nums) {
    if (obj[n]) {
      obj[n]++;
    } else {
      obj[n] = 1;
    }
  }
  let cows = Object.keys(obj).map(id => ({id, count: obj[id]}));
  cows.sort((a, b) => b.count - a.count);
  return cows.slice(0, k).map(cow => Number(cow.id)).sort((a, b) => a - b);
}
module.exports = {
  most_popular_cows: most_popular_cows,
};