1019. 数字黑洞 (20)

#include<stdio.h>void swap1(int *a, int *b){  int temp;  temp = *a;  *a = *b;  *b = temp;}int x=0,big=0,small=0,a[4],s;void fun(int x){  int i,j;  a[0] = x%10;  a[1] = x%100/10;  a[2] = x%1000/100;  a[3] = x/1000;  for(i=0; i<3; i++)    for(j=0; j<3-i; j++)      if(a[j]>a[j+1])        swap1(&a[j],&a[j+1]);  big = a[0] + a[1]*10 + a[2]*100 + a[3]*1000;  small = a[3] + a[2]*10 + a[1]*100 + a[0]*1000;}int main(){  scanf("%d",&x);  while(s!=6174)  {    fun(x);    s = big - small;    printf("%04d - %04d = %04d\n",big,small,s);    if(s==0)      break;    x = s;  }  return 0;}