PlaygroundEvenlyDistribution.java

@Test
public void simpleDistributionTest() {
    // Arrange
    List<String> data = Arrays.asList("red", "red", "blue", "blue", "green", "green");

    // Act
    List<String> result = evenlyDistribute(data);

    // Assert
    List<String> expectation = Arrays.asList("red", "blue", "green", "red", "blue", "green");
    assertEquals(expectation, result);
}

private static List<String> evenlyDistribute(List<String> data) {
    Map<String, List<String>> partitionedData = data.stream()
        .collect(Collectors.groupingBy(Function.identity(), LinkedHashMap::new, Collectors.toList()));

    List<String> distributedData = new ArrayList<>();
    int currentIndex = 0;

    while (distributedData.size() < data.size()) {
        for (Map.Entry<String, List<String>> partition : partitionedData.entrySet()) {
            if (currentIndex == partition.getValue().size()) {
                partitionedData.remove(partition.getKey());
                continue;
            }

            distributedData.add(partition.getValue().get(currentIndex));
        }

        currentIndex++;
    }

    return distributedData;
}