Minimum Operations to Make the Array K-Increasing LeetCode solution in Java

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class Solution {
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  public int kIncreasing(int[] arr, int k) {
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    int ans = arr.length;
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    int[] tails = new int[arr.length];
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    for (int i = 0; i < k; i++) {
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      int size = 0;
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      for (int j = i; j < arr.length; j += k) {
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        if (size == 0 || arr[j] >= tails[size - 1]) {
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          tails[size++] = arr[j];
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        } else {
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          int low = 0, high = size - 1;
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          while (low <= high) {
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            int mid = (low + high) / 2;
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            if (tails[mid] <= arr[j] && tails[mid + 1] > arr[j]) {
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              tails[mid + 1] = arr[j];
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              break;
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            } else if (tails[mid + 1] <= arr[j]) {
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              low = mid + 1;
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            } else {
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              high = mid - 1;
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            }
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          }
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          if (low > high) {
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            tails[0] = arr[j];
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          }
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        }
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      }
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      ans -= size;
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    }
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    return ans;
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  }
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}