1497.js

/** ------------------------------------------------------------------------------
 * 
 * 1497. Check If Array Pairs Are Divisible by k
 * Topics: Hash Table
 * https://leetcode.com/problems/check-if-array-pairs-are-divisible-by-k/description/?envType=daily-question&envId=2024-10-01
 * 
 ------------------------------------------------------------------------------ */
/**
 * @param {number[]} arr
 * @param {number} k
 * @return {boolean}
 */
var canArrange = function (arr, k) {
  const freq = new Array(k).fill(0)

  for (const num of arr) {
    let rem = num % k

    if (rem < 0) {
      rem += k
    }
    freq[rem]++
  }

  if (freq[0] % 2 !== 0) {
    return false
  }

  for (let i = 1; i <= Math.floor(k / 2); i++) {
    if (freq[i] !== freq[k - i]) {
      return false
    }
  }

  return true
}

// console.log(canArrange([1, 2, 3, 4, 5, 10, 6, 7, 8, 9], 5))
console.log(canArrange([1, 2, 3, 4, 5, 6], 7))