Minimum Adjacent Swaps for K Consecutive Ones LeetCode solution in Java

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class Solution {
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  public int minMoves(int[] nums, int k) {
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    var gaps = new ArrayList<Integer>();
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    for (int i = 0, last = -1; i < nums.length; ++i) {
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      if (nums[i] == 1) {
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        if (last > -1) {
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          gaps.add(i - 1 - last);
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        }
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        last = i;
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      }
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    }
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    int lsum = 0, rsum = 0, wlsum = 0, wrsum = 0;
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    for (int i = k / 2 - 1; i >= 0; --i) {
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      lsum += gaps.get(i); // lsum = 3+0
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      wlsum += lsum; // wlsum = 1*3+2*0
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    }
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    for (int i = k / 2; i < k - 1; ++i) {
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      rsum += gaps.get(i); // rsum = 2+5
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      wrsum += rsum; // wrsum = 2*2+1*5
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    }
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    int ans = wlsum + wrsum;
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    for (int p = 0, q = k / 2, r = k - 1; r < gaps.size(); ++p, ++q, ++r) {
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      wlsum += (k / 2) * gaps.get(q) - lsum;
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      lsum += gaps.get(q) - gaps.get(p);
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      rsum += gaps.get(r) - gaps.get(q);
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      wrsum += rsum - ((k - 1) / 2) * gaps.get(q);
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      ans = Math.min(ans, wlsum + wrsum);
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    }
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    return ans;
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  }
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}