神奇算式

由4个不同的数字,组成的一个乘法算式,它们的乘积仍然由这4个数字组成.

比如:210*6=1260,8*473=3784,27*81=2187都符合要求

如果满足乘法交换律的算式算作同一种情况,那么,一共有多少种满足?

#include <stdio.h>
int issame(int a,int b,int c,int d)
{
    if(a == b || a == c || a == d )
        return 1;
    if(b == c || b == d || c == d)
        return 1;
    return 0;
}
int isincluded(int t,int a,int b,int c,int d)
{
    int a1,b1,c1,d1;
    int mark = 0;
    //取每位数
    a1 = t%10;
    t/=10;
    b1 = t%10;
    t/=10;
    c1 = t%10;
    d1 = t/10;
    if(!issame(a1,b1,c1,d1))
    {
        if(a1 == a || a1 == b || a1 == c || a1 == d)
            mark ++;
        if(b1 == a || b1 == b || b1 == c || b1 == d)
            mark ++;
        if(c1 == a || c1 == b || c1 == c || c1 == d)
            mark ++;
        if(d1 == a || d1 == b || d1 == c || d1 == d)
            mark ++;
        if(mark == 4)
            return 1;
    }
    return 0;
}
int main() 
{
    int a,b,c,d,t;
    int count = 0;
    //a*bcd
    for(a=2;a<=9;a++)
        for(b=1;b<=9;b++)
            for(c=0;c<=9;c++)
                for(d=0;d<=9;d++)
                {
                    if(!issame(a,b,c,d))
                    {
                        t = a*(100*b+10*c+d);
                        if(t/1000 > 0 && isincluded(t,a,b,c,d))//4位数,且由a,b,c,d组成
                        {
                            printf("%d*%d=%d
",a,t/a,t);
                            count ++;
                        } 
                    }
                }
    //ab*cd(ab<cd)
    for(a=1;a<=9;a++)
        for(b=0;b<=9;b++)
            for(c=2;c<=9;c++)//判断语句不可写为:c>a && c<=9,否则a=2时就会跳过搜索了,导致搜索到的最大的数 为1999 
                for(d=0;d<=9;d++)
                {
                    if(c > a && !issame(a,b,c,d))//c要大于a 
                    {
                        t = (10*a+b)*(10*c+d);
                        if(t/1000 >0 && isincluded(t,a,b,c,d))
                        {
                            printf("%d*%d=%d
",10*a+b,10*c+d,t);
                            count ++;
                        }
                    }
                }
    printf("共计:%d
",count);
    return 0;
}