地址如下：http://songjindian.javaeye.com/blog/649805

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main(void)
{
	char	gesture[3][10] = {"scissor", "stone", "cloth"};
	int		man, computer, result, ret;

	srand(time(NULL));
	while(1)
	{
		computer = rand()%3;
		printf("\n Input your gesture(0-scissor 1-stone 2-cloth):\n");
		ret = scanf("%d", &man);
		if(ret != 1 || man < 0 || man > 2)
		{
			printf("Invalid input!\n");
			return 1;
		}
		printf("Your gesture : %s\tComputers getsture: %s\n",
				gesture[man], gesture[computer]);

		result = (man - computer + 4) % 3 - 1;
		printf("result = %d\n ", result);
		if( result > 0)
			printf ("You win!\n");
		else if( result == 0 )
			printf("Draw!\n");
		else 
			printf("You lose!\n");
	}
	return 0;
}

分析如下：

人：  0  1  2
电脑：0  1  2

结果：  (0-0+4)%3-1=0    (0-1+4)%3-1=-1   (0-2+4)%3-1=1
 (1-0+4)%3-1=1    (1-1+4)%3-1=0    (1-2+4)%3-1=-1
 (2-0+4)%3-1=-1   (2-1+4)%3-1=1    (2-2+4)%3-1=0