Maximum Points You Can Obtain from Cards LeetCode solution in Java

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class Solution {
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  public int maxScore(int[] cardPoints, int k) {
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    int n = cardPoints.length;
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    int[] totalSum = new int[n];
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    int sum = 0;
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    for (int i = 0; i < n; i++) {
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      sum += cardPoints[i];
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      totalSum[i] = sum;
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    }
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    if (n == k) {
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      return sum;
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    }
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    int score = 0;
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    for (int i = 0; i <= k; i++) {
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      int j = i + n - k - 1;
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      int subsum = 0;
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      if (i == 0) {
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        subsum = totalSum[j];
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      } else {
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        subsum = totalSum[j] - totalSum[i - 1];
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      }
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      score = Math.max(score, sum - subsum);
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    }
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    return score;
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  }
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}