Minimum Cost of Buying Candies With Discount LeetCode solution in Java

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class Solution {
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  /**
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   * Algorithm 1. Sort the cost array. 2. In a loop, start from the back and buy items n, n-1 to get
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   * n-2 for free. 3. Decrement the position by 3 and continue. stop when you reach 1. 4. From 1,
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   * add the remaining 1 or 2 items.
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   */
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  public int minimumCost(int[] cost) {
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    int minCost = 0;
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    int index = cost.length - 1;
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    Arrays.sort(cost);
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    // add items in pairs of 2, the 3rd one getting it for free.
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    while (index > 1) {
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      minCost += cost[index] + cost[index - 1];
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      index -= 3;
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    }
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    // add the remaining 1, 2 items, if any.
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    while (index >= 0) {
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      minCost += cost[index--];
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    }
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    return minCost;
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  }
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}