寒武纪测试赛1-C题

代码：

#include<iostream>
#include<math.h>
using namespace std;
int a[100001] = { 0 };
int main()
{
    int N;
    while (cin >> N)
    {
        int sum = N - 2;
        int i = 2;
        while (1)
        {
            if (a[i] == 0)
            {
                a[i] = pow(i + 1, 2)-1;
            }
            if (N >= a[i])
            {
                sum += (N - a[i]) / i + 1;
            }
            else
            {
                break;
            }
            i++;
        }
        cout << sum << endl;
    }
    return 0;
}

#include<iostream>
#include<math.h>
using namespace std;
int main()
{
    int N;
    while (cin >> N)
    {
        if (N <= 2)
        {
            printf("0
");
            continue;
        }
        long long sum = N - 2;
        for (long long i = 2; (i + 1)*(i + 1) - 1 <= N; i++)
        {
            sum += (N - (i + 1)*(i + 1) + 1 + i)/i;
        }
        printf("%lld
", sum);
    }
    return 0;
}