Josephus

#include <stdio.h>


int survivor(int circle_size, int kill )
{
    if (circle_size ==1 ) return 1;
    int s= survivor(circle_size-1, kill) + kill;
    s = (s-1)%circle_size +1; //wrapping around circle (1,2...circle_size)
    return s;
}


int i_th_last_survivor(int circle_size, int kill, int n_surv, int who)
{
    if (circle_size == n_surv ) return who;
    int s= i_th_last_survivor(circle_size-1, kill, n_surv, who) + kill;
    s = (s-1)%circle_size +1; //wrapping around circle (1,2...circle_size)
    return s;
}


void simulation(int circle_size, int kill, int n_show)
{
    int people[circle_size];
    int last_circle_size = circle_size;
    int i;

    for (i=0;i<circle_size;i++)
        people[i]=i+1;

    int read=0, write=0;
    int counter=1;
    while (circle_size>0)
    {
        if ((counter++)%kill==0){
            if (circle_size<=n_show)
                printf("%d indicated as %dth from the end\n",people[read],circle_size);
            read++;
            circle_size--;

        }else
            people[write++]=people[read++];
        if (read>=last_circle_size ){
            read=0;
            write=0;
            last_circle_size  = circle_size;
        }
    }
}




int main(void)
{
    printf("Flavius: %d\n",survivor(41,3));
    printf("Hungry Lu: %d\n",survivor(100,5));
    printf("Flavius and his friend: %d %d\n\n",i_th_last_survivor(41,3,2,1),i_th_last_survivor(41,3,2,2));
    printf("Flavius:\n");
    simulation(41,3,4);
    printf("Monks:\n");
    simulation(100,5,4);

    return 0;
}