#import "MergeSort.h"

@implementation MergeSort

+ (NSMutableArray *)execute:(NSMutableArray *)numbers

start:(NSInteger)start

end:(NSInteger)end {

if (start < end) {

long middle = (start + end) / 2;

numbers = [self execute:numbers start:start end:middle];

numbers = [self execute:numbers start:middle + 1 end:end];

numbers = merge(numbers, (int)start, (int)middle, (int)end);

}

return numbers;

}

NSMutableArray *merge(NSMutableArray *list, int start, int middle, int end) {

int reverseNavigator = middle - 1;

while (reverseNavigator >= 0) {

int trailer = reverseNavigator;

int forwardNavigator = trailer + 1;

for (int i = forwardNavigator; i < end; i++) {

if (list[trailer] < list[i]) {

id temp = list[trailer];

list[trailer] = list[i];

list[i] = temp;

trailer++;

} else {

break;

}

}

reverseNavigator--;

}

return list;

}