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  1. Count Triplets
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Count Triplets

  • khalid_hamdaan
     + 0 comments

    Why is this failing hidden test case 6 :(

    I came up with idea of moving forward and keeping a track of singles and doubles that have happened. This is passing all test cases except test case 6 :(

    static long countTriplets(List<long> arr, long r)
{
    Dictionary<long, long> singles = new();
    Dictionary<long, long> doubles = new();
    long count = 0;

    foreach (var num in arr)
    {
        long keyByr = num / r;

        // If num completes a triplet
        if (doubles.ContainsKey(keyByr))
        {
            count += doubles[keyByr];
        }

        // If num can be a middle of triplet
        if (singles.ContainsKey(keyByr))
        {
            if (doubles.ContainsKey(num))
                doubles[num] += singles[keyByr];
            else
                doubles[num] = singles[keyByr];
        }

        // Count num as potential start
        if (singles.ContainsKey(num))
            singles[num]++;
        else
            singles[num] = 1;
    }

    return count;
}