五种颜色的球若干个，从中取三个球，三球颜色不同的组合。

#include<stdio.h>
int main()
{
 enum Color{red,yellow,blue,white,black};                   //声明枚举类型enum Color
 enum Color i,j,k,pri;                                      //定义枚举变量i，j，k，pri
 int n,loop;
 n=0;
 for(i=red;i<=black;i++)
  for(j=red;j<=black;j++)
   if(i!=j)
   {
    for(k=red;k<=black;k++)
     if((k!=i)&&(k!=j))
     {
      n++;                                    //符合条件加1
      printf("%-4d",n);                       //输出第几个符合条件的组合
      for(loop=1;loop<=3;loop++)              //使把i,j,k的值赋值给pri，也就是把枚举类型中的颜色赋值给pri
      {
       switch(loop)
       {
       case 1: pri=i;break;
       case 2: pri=j;break;
       case 3: pri=k;break;
       default: break;
       }
       switch(pri)                                //输出各种颜色
       {
       case red:printf("%-10s","red");break;
       case yellow:printf("%-10s","yellow");break;
       case blue:printf("%-10s","blue");break;
       case white:printf("%-10s","white");break;
       case black:printf("%-10s","black");break;
       default:break;
       }
      }
      printf("\n");
     }
   }
     
 
 printf("总计：%d\n",n);                                         //输出总有多少种组合
 return 0;
}