Search for the biggest amplitude in an array
Some key points:


No need to sort the array to find min/max value
No need to copy the array, can search in the original array using an offset count * N


Have a look at this:

public String solution(int[] T) {
    final int count = T.length / 4;
    int indx = 0;
    int last = Integer.MIN_VALUE;
    for (int i = 0; i &lt; 4; ++i) {
        int diff = IntStream.of(T).skip(count * i).limit(count).max().getAsInt()
                 - IntStream.of(T).skip(count * i).limit(count).min().getAsInt();
        if (diff &gt; last) {
            indx = i;
            last = diff;
        }
    }
    final String[] seasons = { "WINTER", "SPRING", "SUMMER", "AUTUMN" };
    return seasons[indx];
}