Q10015: Joseph's Cousin

/*
    質數選法用sieve
    要讓跑的次數少一點
    不然會很沒有效率
    Run time: 0.030
*/
#include <stdio.h>
#define N 32610
int prime[3500];
bool isprime[N];
void assignPrime();
int test(int n);

int main()
{
    assignPrime();
    int n;
    int survivor;
    while (scanf("%d", &n))
    {
        if (!n) break;

        survivor = test(n);
        printf("%d\n", survivor);
    }
    return 0;
}

void assignPrime()
{
    int i, j;

    for ( i = 2; i*i <= N; i++)
        if (!isprime[i])
            for ( j = 2*i; j <= N; j+=i)
                isprime[j] = true;

    for ( i = 2, j = 0; i <= N; i++)
        if (!isprime[i])
            prime[j++] = i;
}

int test(int n)
{
    int left = n;
    int count;
    int index = 0;
    int i, j;
    bool arr[n];

    for ( i = 0; i < n; i++)
        arr[i] = true;

    for ( i = 0; i < n-1; i++)
    {
        count = (left < prime[i]) ? prime[i]%left : prime[i];

        for ( j = 0; j < count; index++)
        {
            if (index == n)
                index = 0;

            if (arr[index])
                j++;
        }

        arr[--index] = false;
        index++;
        left--;
    }

    for ( i = 0; i < n; i++)
        if (arr[i])
            return (i+1);
}