1069. The Black Hole of Numbers (20)

#include <iostream>
#include <string.h>
#include <algorithm>

using namespace std;

int cmp(char a, char b)
{
	return a > b;
}

int main()
{
	int num[2];
	scanf("%d", &num[0]);

	char s[5];
	while(1)
	{
		sprintf(s, "%04d", num[0]);
		sort(s, s + 4, cmp);
		sscanf(s, "%d", &num[0]);
		printf("%s - ", s);
	
		sort(s, s + 4);
		printf("%s = ", s);
		sscanf(s, "%d", &num[1]);

		num[0] -= num[1];
		printf("%04d\n", num[0]);

		if(num[0] == 0 || num[0] == 6174)
		{
			break;
		}
	}

	system("pause");
	return 0;
}