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  1. Prepare
  2. Tutorials
  3. 30 Days of Code
  4. Day 19: Interfaces
  5. Discussions

Day 19: Interfaces

  • maxvetrov555
     + 1 comment

    I added some optimisations(there is the half of operations if the number n is odd).

    What do you think about it?

    class Calculator : public AdvancedArithmetic {
public:
    int divisorSum(int n) {
        int sum = n + 1;
        const int s = sqrt(n);
        const int di = 1 + (n & 1);

        for(int i = di + 1; i <= s; i += di) {
            if (n % i == 0) {
                sum += i + n / i;
            }
        }

        if (s * s == n) sum -= s;
        return sum;
    }
};