A1069 . The Black Hole of Numbers (20)

#include<cstdio>#include<cstring>#include<algorithm>//仔细观察，合并using namespace std;bool cmp(char c1,char c2){return c1 > c2;}int main(){int n,n1,n2;char str[5];scanf("%d",&n);while(1){sprintf(str,"%04d",n);int len = strlen(str);sort(str,str+len);sscanf(str,"%d",&n1);sort(str,str+len,cmp);sscanf(str,"%d",&n2);n = n2 - n1;printf("%04d - %04d = %04d\n",n2,n1,n);if(n==0 || n == 6174) break;}return 0;}