杨辉三角打印

- (NSMutableArray*)printS:(NSInteger)n {
    NSMutableArray* array = [NSMutableArray array];
    
    if (n == 1) {
        [array addObject:@(1)];
        [array addObject:@(1)];
        
    } else {
        NSMutableArray* fowardArray = [self printS:n - 1];
        for (int i = 0; i <= [fowardArray count]; i++) {
            if (i == 0) {
                [array addObject:fowardArray[0]];
                
            } else if ( i == [fowardArray count]) {
                [array addObject:[fowardArray lastObject]];
                
            } else {
                [array addObject:@([[fowardArray objectAtIndex:i-1] integerValue] + [[fowardArray objectAtIndex:i] integerValue])];
            }
        }
    }
    
    for (int i = 0; i < [array count]; i++) {
        printf("  %ld", [[array objectAtIndex:i] integerValue]);
    }
    printf("\n");
    
    return array;
}