C语言经典案例(1~~3)
(1)题目:有1、2、3、4个数字,能组成多少个互不相同且无重复数字的三位数?都是多少?
/* Note:Your choice is C IDE */
#include "stdio.h"
void main()
{ int j,k,l,sum=0;
for(j=1;j<=4;j++)
{ for(k=1;k<=4;k++)
{
if(j==k)
continue;
for(l=1;l<=4;l++)
{
if(l==j||l==k)
continue;
sum=j*100+k*10+l;
printf("%d\n",sum);
}
}
}
}
(2)题目:一个整数,它加上100后是一个完全平方数,再加上168又是一个完全平方数,请问该数是多少?
/* Note:Your choice is C IDE */
#include "stdio.h"
#include "math.h"
main()
{ int i,num1=0,num2=0;
for(i=0;i<100000;i++)
num1=i+100;
num2=i+268;
{if(sqrt(pow(num1,2))==i+100&&sqrt(pow(num2,2))==i+268)
printf("%10d",i);
}
}
(3)题目:输入某年某月某日,判断这一天是这一年的第几天?
/* Note:Your choice is C IDE */
#include "stdio.h"
main()
{
int i,year,month,day,sum=0;
printf("请输入年,月,日\n");
scanf("%d,%d,%d",&year,&month,&day);
for(i=1;i<month;i++)
switch(i)
{
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:
sum=sum+31;
break;
case 2:
if(year%4==0||year%100==0&&year%400==0)
sum=sum+29;
else
sum=sum+28;
break;
case 4:
case 6:
case 9:
case 11:
sum=sum+30;
break;
default:printf("data error");break;
}
printf("这是第%d天.",sum+day);
}