Given an array of integers and integer K, return another array holding integers appeared K times in the given array

Question

Avadesh Kumar · Accepted Answer

NSArray *array =  [self getElementsFromArray:@[@1, @3, @3, @1, @2, @3, @4, @1, @2] whereElementCountIsGreaterThan:1];

- (NSArray *)getElementsFromArray:(NSArray *)allElements whereElementCountIsGreaterThan:(NSInteger)frequency
{
    NSCountedSet *countedSet = [NSCountedSet setWithArray:allElements];
    
    NSMutableArray *finalElements = [[NSMutableArray alloc] init];
    
    for (NSNumber *item in countedSet) {
    
        if ([countedSet countForObject:item] > frequency) {
        
            [finalElements addObject:item];
        }
    }
    
    return  finalElements;
}

Khawaja Farooq · Answer

- (NSArray *)findElements:(NSArray*)array withK:(int)kTimes
{
    NSMutableArray *resultArray = [NSMutableArray array];
    
    NSMutableDictionary *dict = [NSMutableDictionary dictionary];
    
    for (NSNumber *number in array) {
        
        if ([dict objectForKey:number.stringValue]) {
            
            NSInteger count = [[dict objectForKey:number.stringValue] integerValue];
            [dict setValue:[NSNumber numberWithInteger:count+1] forKey:number.stringValue];
        }
        else {
            
            [dict setValue:[NSNumber numberWithInteger:1] forKey:number.stringValue];
        }
    }
    
    for (NSString *key in dict) {
        
        NSInteger count = [[dict objectForKey:key] integerValue];
        
        if (count == kTimes) {
            [resultArray addObject:key];
        }
    }
    
    return resultArray;
}

Deepali Maheshwari · Answer

func solution(_ nums: [Int], _ k: Int) -> [Int] {
        var dict = [Int: Int]()
        for num in nums {
            dict[num, default: 0] += 1
        }
        return Array(dict.filter { $0.value == k }.map {$0.key})
    }

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