Minimum Rounds to Complete All Tasks LeetCode solution in Java

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/**
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 * Each round, we can complete either 2 or 3 tasks of the same difficulty level Time: O(n) Space:
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 * O(n)
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 */
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class Solution {
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  public int minimumRounds(int[] tasks) {
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    int round = 0;
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    Map<Integer, Integer> taskMap = new HashMap<>(); // map of <task,  number of each task>
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    for (int i = 0; i < tasks.length; i++) {
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      taskMap.put(tasks[i], taskMap.getOrDefault(tasks[i], 0) + 1);
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    }
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    for (Map.Entry<Integer, Integer> entry : taskMap.entrySet()) {
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      if (entry.getValue() == 1) {
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        return -1; // we cannot complete if there is only 1 task
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      }
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      // try to take as many 3's as possible
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      round += entry.getValue() / 3;
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      /*
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      We can have 1 or 2 tasks remaining. We're not supposed to take task of count 1, but we can 'borrow' 1 from the previous
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      ex. [5,5,5,5,5,5,5] -> [5,5,5][5,5,5][5]
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      In this example, treat the last [5,5,5], [5] as [5,5], [5,5]
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              */
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      if (entry.getValue() % 3 != 0) {
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        round++;
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      }
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    }
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    return round;
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  }
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}