Minimum Swaps to Group All 1's Together II LeetCode solution in C++

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class Solution {
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 public:
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  int minSwaps(vector<int> &nums) {
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    int n = nums.size();
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    int ones = 0; // total no. of ones
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    for (int i = 0; i < n; i++) {
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      if (nums[i] == 1) ones++;
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    }
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    if (ones <= 1) return 0;
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    int k = ones;    // sliding window length
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    int maxOnes = 0; // maxOnes in sub array of length k
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    int cnt = 0;
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    for (int i = 0; i < k; i++) {
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      if (nums[i] == 1) cnt++;
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    }
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    maxOnes = cnt;
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    for (int i = k; i < n + k; i++) {
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      if (nums[i - k] == 1) cnt--; // if element removing from window is 1, then decrease count.
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      if (nums[i % n] == 1) cnt++; // if element adding to window is 1, then increase count.
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      maxOnes = max(maxOnes,
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                    cnt); // maintaing maxOnes for all sub arrays of length k.
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    }
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    return (k - maxOnes); // (total length of subarray - ones in the sub array found)
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  }
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};