ExamAengin

gistfile1.txt

// JAVA 
// QUESTION 1
static String getReverseString(String input) {
    char[] in = input.toCharArray();
    char buff;
    for (int i=0,j=input.length()-1; i<input.length()/2;i++,j--) {
        buff = in[i];
        in[i] = in[j];
        in[j] = buff;
    }
    return new String(in);
}

// Using .....
// String s  = "hello";
// String rs = getReverseString(s); 
//

// QUESTION 2
static int _result = 999999999;
static void getMinValue(int[][] input) {
    _result = 999999999;
    for (int y=0; y<input.length; y++) {
        forceSolve(input, 0, 0, input[0].length);
    }
}

static void forceSolve(int[][] input, int indexX, int buff, int maxDepth) {
    if (indexX >= maxDepth) {
        if (buff < _result) {
            _result = buff;
        }
        return;
    }

    for (int y=0; y<input.length; y++) {
        int _buff = input[y][indexX] + buff;

        forceSolve(input, indexX+1, _buff, maxDepth);
    }
}

// Using .....
// int[][] data = .....
// getMinValue(data);
// int ans = _result;

// Objective C
// QUESTION 3
@interface Beacon : NSObject
@property (atomic, strong) NSString *beaconId;
@property (atomic, strong) NSNumber *timestamp;
@property (atomic, strong) NSData *data;
- (void)setCurrentTime;
@end

@implementation Beacon

- (instancetype)initWithData:(NSString *)beaconId withData:(NSData *)data {
    if (self = [super init]) {
        self.data = data;
        [self setCurrentTime];
    }
    return self;
}

- (void)setCurrentTime {
    unsigned long long timeInMiliseconds = (unsigned long long)[[NSDate date] timeIntervalSince1970];
    _timestamp = [NSNumber numberWithUnsignedLongLong:timeInMiliseconds];
}

- (BOOL) isOverTime {
    const unsigned long long INTERVAL_TIME = 10; //10 sec
    const unsigned long long now = (unsigned long long)[[NSDate date] timeIntervalSince1970] - INTERVAL_TIME;
    return now > [_timestamp unsignedLongLongValue];
}
@end

@interface Manager : NSObject
+(Manager *) getInstance;
@property (atomic, strong) NSTimer *timer;
@property (atomic, strong) NSMutableDictionary<NSString *, Beacon *> *list;
@end

@implementation Manager

static Manager* instance;

+(Manager *) getInstance
{
    static dispatch_once_t token;
    dispatch_once(&token, ^{
        instance = [[Manager alloc] init];
    });
    return instance;
}

- (id)init {
    self = [super init];
    if(self){
        self.list = [NSMutableDictionary new];
        self.timer = [NSTimer scheduledTimerWithTimeInterval:1
                                                      target:self
                                                    selector:@selector(checkTime)
                                                    userInfo:nil
                                                     repeats:YES] ;
    }
    return self;
}

- (void)setBeacon:(Beacon *)beacon {
    if (beacon.beaconId == nil) { return; }
    
    if ([self.list objectForKey:beacon.beaconId]) {
        Beacon *bc = [self.list objectForKey:beacon.beaconId];
        [bc setCurrentTime];
        
    } else {
        [self.list setObject:beacon forKey:beacon.beaconId];
    }
}

- (void)checkTime {
    NSArray *keys = [self.list allKeys];
    NSMutableArray *temp = [NSMutableArray new];
    for (NSString *key in keys) {
        if ([self.list objectForKey:key] == nil) { continue; }
        Beacon *buff = [self.list objectForKey:key];
        if ([buff isOverTime]) {
            [temp addObject:buff.beaconId];
        }
    }

    if ([temp count] > 0) {
        [[NSNotificationCenter defaultCenter] postNotificationName:@"beacon_timeout" object:self userInfo:@{@"beacons": temp}];
    }
}

@end