实验2

task1

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

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

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

21 抽397到476的同学
25 0 21
随机抽取在座的5名同学

task2

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#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;
}

task3

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#include<stdio.h>

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

================================================================================================
task4

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#include<stdio.h>

int main()
{

	double pay , sum = 0.0 , max=0.0 , min=20000.0;
	
	printf("输入今天的开销直至-1终止\n");
	while((scanf("%lf",&pay)) != EOF )
	{
		
		if(pay == -1)
			break;
			
		sum = sum + pay;
		
		if(pay > max)
			max = pay;
			
		if(pay < min)
			min = pay;
			
		
	}
	
	printf("最高一笔开销%lf\n最低一笔开销%lf\n一天总开销%lf\n",max,min,sum);
}

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#include<stdio.h>

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


=============================================================================================================

task6

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#include<stdio.h>

#define N 1
#define N1 30

int main()
{
	int luck,i,gus;
	i = 0;
	
	srand(time(NULL));
	luck = rand() % ( N1 - N + 1) + 1;
	
	printf("开始喽，你有三次机会，猜吧（1~30）：");
	while ( i < 3 )
		{
			scanf("%d",&gus);
			
			if     (gus < luck)
				printf("你猜的日期早了，你的luck日在后面哦\n");
			else if(gus = luck)
			{
				printf("哇猜中了：）");
				break;
			}
			else
				printf("你猜的日期晚了，你的luck日在前面哦\n");
				
			
			if (i < 2)
				printf("在猜（1~30）：");
			else if(i == 2)
				printf("次数用完了。偷偷告诉你，11月你的luck day是%d号哦",luck);
			
			i++;
		}

	
	return 0;
		 
}