#include <stdio.h>
#include <time.h>
#include <stdbool.h>

#define DEAD true
#define ALIVE false

bool people[40] = {0};

void iteration() {
    int nowCount = 0, nowPos = 0, nowDead = 0;
    while (nowDead < 39) {
        nowCount = 0;
        while (nowCount < 3) {
            if (people[nowPos % 40]==ALIVE) {
                nowCount++;
            }
            nowPos++;
        }
        people[(nowPos+39)%40] = DEAD;
        nowDead+=1;
    }
    for (nowPos = 0; nowPos < 40; nowPos++) {
        if (people[nowPos % 40] == ALIVE) {
            printf("Stand at %d\n", nowPos+1);
            break;
        }
    }
}

int recursion(int nowDead, int nowPos) {
    int nowCount=0;
    if (nowDead == 39) {
        for (nowPos = 0; nowPos < 40; nowPos++) {
            if (people[nowPos % 40] == ALIVE) {
                // printf("Stand at %d\n", nowPos+1);
                return nowPos;
            }
        }
    }
    else {
        while (nowCount < 3) {
            if (people[nowPos % 40]==ALIVE) {
                nowCount++;
            }
            nowPos++;
        }
        people[(nowPos+39)%40] = DEAD;
        return recursion(nowDead+1, nowPos);
    }
}

int main() {
    int startTime, finishTime;
    double time;
    int i = 0;
    startTime = clock();
    iteration();
    finishTime = clock();
    time = ((double)(finishTime - startTime))/CLOCKS_PER_SEC;
    printf("Time elapsed: %lfs\n", time);

    for (i = 0; i < 40; i++) {
        people[i] = ALIVE;
    }

    startTime = clock();
    printf("Stand at %d\n",recursion(0,0)+1);
    finishTime = clock();
    time = ((double)(finishTime - startTime))/CLOCKS_PER_SEC;
    printf("Time elapsed: %lfs", time);
    return 0;
}