3208.js

/** ------------------------------------------------------------------------------
 * 
 * 3208. Alternating Groups II
 * Topics: Sliding Window
 * https://leetcode.com/problems/alternating-groups-ii/description/?envType=daily-question&envId=2025-03-09
 * 
 ------------------------------------------------------------------------------ */
/**
 * @param {number[]} colors
 * @param {number} k
 * @return {number}
 */
var numberOfAlternatingGroups = function (colors, k) {
  for (let i = 0; i < k - 1; i++) colors.push(colors[i])
  let res = 0,
    cnt = 1
  for (let i = 1; i < colors.length; i++) {
    if (colors[i] != colors[i - 1]) cnt++
    else cnt = 1
    if (cnt >= k) res++
  }

  return res
}

console.log(numberOfAlternatingGroups([1, 2, 1, 2, 1], 2))