[Solved] C++ Program Bug [closed]

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I simply used a hash to store the frequencies of remainders when divided by 7:

int count7Divisibiles(int arr[], int n)
{
    // Create a frequency array to count 
    // occurrences of all remainders when 
    // divided by 7
    int freq[7] = {0, 0, 0, 0, 0, 0, 0};

    // Count occurrences of all remainders
    for (int i = 0; i < n; i++)
        ++freq[arr[i] % 7];

    // If both pairs are divisible by '7'
    int ans = freq[0] * (freq[0] - 1) / 2;


    // If one of them is equal
    // to 1 modulo 7 and the
    // other is equal to 3 
    // modulo 7
    ans += freq[1] * freq[6];

    // for 2%7 and 5%7
    ans += freq[2] * freq[5];

    //for 3%7 and 4%7
    ans += freq[3] * freq[4];

    return ans;
}
  • If both are divisible by 7, then use n*(n-1)/2
  • Else do count(a%7)*count((7-a)%7)

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solved C++ Program Bug [closed]