Pairs — HackerRank Medium (Search)

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The problem requires us to find the number of pairs that result in the target value when subtraction is performed.

The approach I am using here is,

For example we are given a set of 1 3 5 8 6 4 2. If we add the target value e.g 2 to each element, we get a new set of 3 5 7 10 8 6 4. If we count the intersected elements between these two sets we get the required count of possible pairs.

static int pairs(int k, int[] arr) {
        int count = 0;
        HashSet<Integer> hset = new HashSet<>();
        for(int i = 0; i < arr.length; i++){
            hset.add(arr[i]);
            arr[i] = arr[i] + k;
        }
        for(int i: arr){
            if(hset.contains(i)){
                count++;
            }
        }
        return count;
    }