实验2

任务1：

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

#define N 5
#define N1 397
#define N2 476
#define N3 21

int main() {
    int cnt;
    int random_major, random_no;

    srand(time(NULL));

    cnt = 0;
    while(cnt < N) {
        random_major = rand() % 2;

        if(random_major) {
            random_no = rand() % (N2 - N1 + 1) + N1;
            printf("20248329%04d\n", random_no);
        }
        else {
            random_no = rand() % N3 + 1;
            printf("20248395%04d\n", random_no);
        }

        cnt++;
    }

    return 0;
}

 问题1：在397到476中取任意一个数

问题2：在1到21中任取一个数

问题3：在一定范围内随机生成5个学号

#include <stdio.h>
#include <math.h>

int main() {
    double a, b, c;
    double delta, p1, p2; 

    while(scanf("%lf%lf%lf", &a, &b, &c) != EOF) {
        if(a == 0) {
            printf("a = 0, invalid input\n");
            continue;
        }

        delta = b*b - 4*a*c;
        p1 = -b/2/a;
        p2 = sqrt(fabs(delta))/2/a;

        if(delta == 0)
            printf("x1 = x2 = %.2g\n", p1);
        else if(delta > 0)
            printf("x1 = %.2g, x2 = %.2g\n", p1+p2, p1-p2);
        else {
            printf("x1 = %.2g + %.2gi, ", p1, p2);
            printf("x2 = %.2g - %.2gi\n", p1, p2);
        }
    }

    return 0;
}

 

 任务3：

#include <stdio.h>

int main()
{
    char a;
    while (scanf("%c", &a) != EOF)
    {
        getchar();
        if (a == 'r')
            printf("stop!\n");
        else if (a == 'g')
            printf("go go go\n");
        else if (a == 'y')
            printf("wait a minute\n");
        else
            printf("something must be wrong\n");
    }
    return 0;
}

 任务4：

#include <stdio.h>

int main()
{
    double m;
    double sum = 0;
    double max = 0;
    double min = 20000;
    printf("输入今日开销，直到输入-1终止:\n");
    while (scanf("%lf", &m) != EOF)
    {
        if (m == -1)
        {
            break;
        }
        else
        {
            sum += m;
            if (m >= max)
            {
                max = m;
            }
            if( m < min)
            {
                min = m;
            }
        }
    }
    printf("今日累计消费总额: %.2lf\n", sum);
    printf("今日最高一笔开销: %.2lf\n", max);
    printf("今日最低一笔开销: %.2lf\n", min);
    return 0;
}

 任务5：

#include <stdio.h>

int main()
{
    int a, b, c;
    while (scanf("%d %d %d", &a, &b, &c) != EOF)
    {
        if (a + b > c && b + c > a && c + a > b)
        {
            if (a * a + b * b == c * c || a * a + c * c == b * b || b * b + c * c == a * a)
            {
                printf("直角三角形\n");
            }
            else if (a == b && b == c)
            {
                printf("等边三角形\n");
            }
            else if (a == b || b == c || a == c)
            {
                printf("等腰三角形\n");
            }
            else
            {
                printf("普通三角形\n");
            }
        }
        else
        {
            printf("不能构成三角形\n");
        }
    }
    return 0;
}

 任务6：

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

int main()
{
    srand(time(NULL));

    int lucky_day = rand() % 30 + 1;
    int cnt = 0;
    int i;
    while (cnt < 3)
    {
        scanf("%d", &i);
        if (i == lucky_day)
        {
            printf("猜中了\n");
            cnt = 3;
            return 0;
        }
        else if (i > lucky_day)
        {
            printf("晚\n");
            cnt++;
        }
        else
        {
            printf("早\n");
            cnt++;
        }
    }
    printf("%d\n", lucky_day);
    return 0;
}