1019 数字黑洞 (20 分)

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

int Ascending(const void *a, const void *b)
{
    return *(int *)a - *(int *)b;
}



int main()
{
    int N;
    scanf("%d", &N);

    int figures[5];
    int i = 0 , j;

    do
    {

        i=0;
        for(i=0;i<4;i++)
        {
            figures[i] = N % 10;
            N = N/10;

        }

        qsort(figures, 4, sizeof(figures[0]), Ascending);

        int A=0, B=0;

        for(i=3;i>=0;i--)
            A = A*10 + figures[i];

        for(i=0;i<4;i++)
            B = B*10 + figures[i];

        N = A - B;
        printf("%04d - %04d = %04d\n", A, B, N);

        if(N == 0)
            break;
    }while(N != 6174);
}