yoman07

- (NSString *) reverseString:(NSString *)str {
    NSMutableString *reverseString = [[NSMutableString alloc] initWithCapacity:str.length];
    
	for(int i=str.length -1;i>=0;i--) {
		[reverseString appendString:[NSString stringWithFormat:@"%c", [str characterAtIndex:i]]];
    }
    return  reverseString;
}

yoman07

- (int) atoi:(char *) str {
    if(!str)
        NSLog(@"Enter valid string");
    
	int result = 0;
    char *p = str;
	while((*p>='0') && (*p<='9')) {
        result = result*10 + (*p - '0');
        p++;
    }

yoman07

- (id) sharedInstance {
	static MyObject *sharedInstance = nil;
	static dispatch_once_t onceToken;
	dispatch_once(&onceToken, ^{
		sharedInstance = [[MyObject alloc] init];
	});
	return sharedInstance;
	
}

yoman07

- (NSArray*) mergeSortArray:(NSArray*) arr {
  	if(arr.count <2) {
		return arr;
    }
    
    NSUInteger middle = arr.count/2;
    NSRange leftRange = {0,middle};
    NSArray *leftArray = [arr subarrayWithRange:leftRange];
    NSRange rightRange = {middle,arr.count-middle};
    NSArray *rightArray = [arr subarrayWithRange:rightRange];

yoman07

- (NSArray*) quickSortArray:(NSArray*) arr {
    
    if(arr.count <2) {
        return arr;
    }
    NSMutableArray *mutableArr = [arr mutableCopy];
    
 
    NSMutableArray *leftArray = [[NSMutableArray alloc] init];
	NSMutableArray *rightArray = [[NSMutableArray alloc] init];