LeetCode/java/minimum-swaps-to-group-all-1s-together-ii.java

class Solution {
  private int countOnes(int[] nums, int upperBound) {
    var count = 0;

    for (int i = 0; i < upperBound; ++i) {
      if (nums[i] == 1) {
        ++count;
      }
    }

    return count;
  }

  public int minSwaps(int[] nums) {
    var ones = countOnes(nums, nums.length);
    var inWindow = countOnes(nums, ones);

    var minSwaps = nums.length;
    for (int i = 0; i < nums.length; ++i) {
      inWindow += nums[(i + ones) % nums.length] - nums[i];

      minSwaps = Math.min(minSwaps, ones - inWindow);
    }

    return minSwaps;
  }
}