C語言-常勝將軍

現在有21根火柴，2人輪流取，每人每次可以取走1~4根，不可多取，也不能不取，誰取最後一根火柴誰輸。編寫一個程序進行人機對弈，要求人先取，計算機後取；計算機一方爲 常勝將軍。

int main(int argc, const char *argv[]) {
    int computer, people, spare = 21;
    printf("-------------------------------\n");
    printf("---------------begin----------------\n");
    printf("-------------------------------\n");
    while (1) {
        printf("---------------- 目前還有火柴%d根--------------\n", spare);
        printf("People:");
        scanf("%d", &people);
        if (people < 1 || people > 4 || people > spare) {
            printf("輸入違規，取得數目有問題！\n\n");
            continue;
        }
        spare -= people;
        if (spare == 0) {
            printf("computer win !Game Over!");
            break;
        }
        computer = 5 - people;
        spare -= computer;
        printf("Computer: %d    \n", computer);
        if (spare == 0) {
            printf("\nPeople win!Game Over!\n");
            break;
        }
    }
 return 0;
}