task.2

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 5
#define N1 374
#define N2 465
int main()
{
int number;
int i;
srand( time(0) ); // 以当前系统时间作为随机种子
for(i = 0; i < N; ++i) {
number = rand()%(N2 - N1 + 1) + N1;
printf("202383290376%04d\n", number);


} return 0;
}

#include<stdio.h>
int main(){
    char n;
    while(scanf("%c",&n)!=EOF){
        getchar();
    switch(n){
        case'r': printf("stop!\n");break;
        case'g': printf("go go go\n");break;
        case'y': printf("wait for a mintue\n");break;
        default: printf("something must be wrong...\n");break;
    } 
    }return 0;
} 

#include<stdio.h>
#include<time.h>
#include<stdlib.h> 
#define N 3
#define N1 1
#define N2 30
int main(){
    int i,n,number;
    i=1,n=3;
    printf("猜猜2023年哪天会是你的lucky day");
    printf("开始了，你有三次机会，猜吧（0~30）") ;
    number=rand()%(N2-N1)+1;
    while(i<N,++i){
    
        scanf("%d",&n);
        if(n<number){
        printf("你猜的日期早了，你的lucky day还没到呢"); 
        printf("再猜（0~30）" );}
        else if(n>number) {
        }
        printf("你猜的日期晚了，你的lucky day已经过了");
        printf("再猜（0~30）" );}
        else{
        printf("哇 猜中了") ;break;}
    }return 0;
} 

#include<stdio.h>
 int main(){
    int n,a,i,t=0;
     double sum=0;
     while(scanf("%d%d",&n,&a)!=EOF){
          for(i=1;i<=n;i++){
             t=t*10+a;
             sum=1.0*i/t+sum; 
          }
         printf("n=%d,a=%d,s=%lf",n,a,sum);
    }
 }

#include<stdio.h>
  int main(){
   int a,b;
      for(a=1;a<=9;a++){
         for(b=1;b<=a;b++)
              printf("%d*%d=%d\t",a,b,a*b);
          printf("\n");
      }
      return 0; } 

 #include<stdio.h>
 int main(){
      int n,a,b,s,m;
      printf("请输入n:");
      scanf("%d",&n);
      m=n;
      for(;n>0;n--){
          for(s=n;s<m;s++)
              printf("\t");
         for(a=2*n-1;a>0;a--){
             printf(" O \t");
             }
        printf("\n");
         for(s=n;s<m;s++)
            printf("\t");
         for(a=2*n-1;a>0;a--){
             printf("<H>\t");
             }
         printf("\n");
        for(s=n;s<m;s++)
             printf("\t");
         for(a=2*n-1;a>0;a--){
             printf("I I\t");
             }
         printf("\n");
     }
     return 0;
 }