实验二

任务一

#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;

}

1.生成397-476的随机数

2.生成1-21的随机数

3.以当前的时间作为随机数函数的种子，随机生成五个随机学号

任务二

#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;
}

任务三

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

任务四

#include<stdio.h>
int main(){
    double sum,max,min,data;
    sum=0;
    max=0;
    min=20000;
    while(scanf("%lf",&data)!=EOF){
        if(data==-1){
            break;
        }
        sum=sum+data;
        if(data>max){
            max=data;
        }
        if(data<min){
            min=data;
        }
    }
    printf("%.1f,%.1f,%.1f",max,min,sum);
    return 0;
}

任务五

#include<stdio.h>
int main(){
    int a,b,c;
    while(scanf("%d %d %d",&a,&b,&c)){
        if(a+b>c&&a+c>b&&b+c>a){
            if(a==b&&b==c){
                printf("等边三角形\n");
            }
            else 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||a==c||b==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");
        }
            
        }
    }

任务六

#include <stdio.h>
int main(){
    int day,i,guess;
    srand(time(NULL));
    day=rand()%30+1;
    printf("猜猜lucky day\n你有三次机会:");
    for(i=0;i<3;i++){
    scanf("%d",&guess);
    if(guess<day){
        printf("早了\n");
        printf("再猜:"); 
    }
    else if(guess>day){
        printf("晚了\n");
        printf("再猜:");
    }
    else{
        printf("猜中了:)");
        return 0;
    }
    }
    printf("\n次数用光了,luckyday是%d号",day);
    return 0;
}