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; //随机生成一个在N1与N2间的数并赋值给 random_no // 
        printf("20248329%04d\n",random_no);
        }
        else{
            random_no = rand() % N3 + 1;//随机生成一个小于N3的数并赋值// 
            printf("20248329%04d\n",random_no);
        }
        cnt++;
        
    }
    
    return 0;
} 
//用于随机生成学号抽签// 

21  随机生成一个在N1与N2间的数并赋值给 random_no

25 随机生成一个小于N3的数并赋值

//用于随机生成学号抽签// 

任务2

// 一元二次方程求解

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

int main() {
    double a, b, c;
    double delta, p1, p2; // 用于保存中间计算结果

    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;
    printf("交通灯颜色是？：\n"); 
    while(scanf(" %c", &a) != EOF){
        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...");
        }
    }
    return 0;
}

任务4

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

int main()
{
    double a, max = 0, min = 20000, zong = 0;
    printf("输入开销：\n"); 
    while(1) {
        scanf("%lf",&a);
        if (a == -1){
        break;
        }
        if (a > max){
        max = a;
        }
        if (a < min){
        min = a;
        }
    zong += a;
        }
        printf("最高开销为%.1lf\n",max);
        printf("最低开销为%.1lf\n",min);
        printf("总开销为%.1lf\n",zong);
    return 0;
}

任务5

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

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

任务6

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

int main ()
{
    int luckyday, guess, attempts = 3;
    srand(time(NULL));
    luckyday = rand() % 30 + 1;
    while (attempts > 0)
    {
        printf("你猜多少（1-30）：");
        scanf("%d",&guess);
        if (guess == luckyday){
            printf("猜对了\n");
            return 0;
    } 
    else if (guess < luckyday){
            printf("猜早了\n");
    }
    else {
            printf("猜晚了\n");
    }
    attempts--;
     } 
     printf("失败了，猜完了，幸运日是%d.\n",luckyday);
     return 0;
}