2134. Minimum Swaps to Group All 1’s Together II

A swap is defined as taking two distinct positions in an array and swapping the values in them.

A circular array is defined as an array where we consider the first element and the last element to be adjacent.

Given a binary circular array nums, return the minimum number of swaps required to group all 1’s present in the array together at any location.

class Solution {
public:
    int minSwaps(vector<int>& A) {
        int res = INT_MAX, count = accumulate(begin(A), end(A), 0), n = A.size();
        for(int i = 0, window = 0; i < 2 * n; i++) {
            if(A[i % n]) window++;
            if(i >= count and A[(i - count + n) % n]) window--;
            if(i >= count - 1) {
                res = min(res, count - window);
            }
        }
        return res;
    }
};