Maximum Value of K Coins From Piles LeetCode solution in Java

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class Solution {
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  public int maxValueOfCoins(List<List<Integer>> piles, int k) {
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    int n = piles.size();
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    int[][] ans = new int[n + 1][2001];
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    Collections.sort(piles, (List<Integer> a, List<Integer> b) -> b.size() - a.size());
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    for (int i = 1; i <= k; i++) {
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      for (int j = 1; j <= n; j++) {
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        int sizeOfPile = piles.get(j - 1).size();
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        List<Integer> pile = piles.get(j - 1);
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        int sum = 0;
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        ans[j][i] = ans[j - 1][i];
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        for (int l = 1; l <= Math.min(i, sizeOfPile); l++) {
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          // Take K from this pile + remaining from previous piles
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          sum += pile.get(l - 1);
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          int rem = i - l;
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          ans[j][i] = Math.max(ans[j][i], sum + ans[j - 1][rem]);
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        }
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      }
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    }
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    return ans[n][k];
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  }
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}