void mergesort(int[] array, int low, int high) {
if (low < high) {
int middle = (low + high) / 2;
mergesort(array, low, middle);
mergesort(array, middle + 1, high);
merge(array, low, middle, high);
}
}
void merge(int[] array, int low, int middle, int high) {
int[] helper = new int[array.length];
for (int i = low; i <= high; i++) {
helper[i] = array[i];
}
int helperLeft = low;
int helperRight = middle + 1;
int current = low;
while (helperLeft <= middle && helperRight <= high) {
if (helper[helperLeft] <= helper[helperRight]) {
array[current] = helper[helperLeft];
helperLeft++;
} else {
array[current] = helper[helperRight];
helperRight++;
}
current++;
}
int remaining = middle - helperLeft;
for (int i = 0; i <= remaining; i++) {
array[current + i] = helper[helperLeft + i];
}
}