四个数从大到小排列
#include<stdio.h>
void main()
{ //from big to small sorting
int a,b,c,d,t;
 scanf("%d%d%d%d",&a,&b,&c,&d);
 if(a<b){t=a;a=b;b=t;}
 if(b<c){t=b;b=c;c=t;}
 if(c<d){t=c;c=d;d=t;}
 if(a<b){t=a;a=b;b=t;}
 if(b<c){t=b;b=c;c=t;}
 if(c<d){t=c;c=d;d=t;}
 if(a<b){t=a;a=b;b=t;}
 if(b<c){t=b;b=c;c=t;}
 if(c<d){t=c;c=d;d=t;}
//以上9个if()可删3个,究竟是哪3个?
 printf("from big to small: %d,%d,%d,%d\n"
 ,a,b,c,d);
}

谢谢了！！！