Unoptimized Permut

permut.m

// unoptimized permute pair elements avoiding repetitions
- (NSArray *) permuteArrayOfSets:(NSArray *)elements {
    NSMutableSet *resultSet = [NSMutableSet set];
    for (NSUInteger i=0;i<[elements count]; i++) {
        for (NSUInteger j=0;j<[elements count]; j++) {
            if (i == j) continue;
            NSSet *newSet = [NSSet setWithObjects:elements[i], elements[j], nil];
            if ([resultSet containsObject:newSet]) continue;
            [resultSet addObject:newSet];
        }
    }
    return [NSArray arrayWithArray:[resultSet allObjects]];
}

// merge set if one of the obj contained in the sets is in another set of elements
- (NSArray *) mergeArrayOfSets:(NSArray *)elements {
    if ([elements count] < 2) return elements;
    // makes all sets mutable
    NSMutableArray *srcArray = [NSMutableArray arrayWithCapacity:[elements count]];
    for (NSSet *s in elements) {
        [srcArray addObject:[NSMutableSet setWithSet:s]];
    }
    
    // add first obj to resArray
    NSMutableArray *resArray = [NSMutableArray array];
    NSSet *oneSet = [srcArray lastObject];
    [resArray addObject:oneSet];
    [srcArray removeObject:oneSet];
    
    NSMutableArray *remainSets = [NSMutableArray array];
    // iterate over srcArray test if one elements from s is in resArray
    for (NSMutableSet *outSet in srcArray) {
        BOOL found = NO;
        for (NSMutableSet *testSet in resArray) {
            if ([outSet intersectsSet:testSet]) {
                [outSet addObject:testSet];
                found = YES;
                break;
            }
        }
        if (!found) {
            for (NSMutableSet *testSet in remainSets) {
                if ([outSet intersectsSet:testSet]) {
                    [outSet addObject:testSet];
                    found = YES;
                    break;
                }
            }
        }
        //otherwise add to remainsArray
        if (!found) {
            [remainSets addObject:outSet];
        }
        
    };
    [resArray addObjectsFromArray:remainSets];
    return resArray;
}