1019. 数字黑洞 (20)

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
	int comp(const void*a,const void*b){
		return *(int*)b-*(int*)a;
	}
	int main(){
		int zqd;
		int o = 0,n = 0;
		int kirby[4] = {0};
		for (int i = 0;i < 4;i++){
			scanf("%1d",&kirby[i]);
		}
//		zqd = kirby[3] + kirby[2] * 10 + kirby[1] * 100 + kirby[0] * 1000;
		zqd = 0;
		qsort(kirby,4,4,comp);
		for (int i = 0;i < 4;i++){
			o += pow(10,i) * kirby[i];
			n += pow(10,i) * kirby[3 - i];
		}
		if (o == n){
			printf("%04d - %04d = 0000\n",n,o);
		}else{
			while(zqd != 6174){
				zqd = n - o;
				printf("%04d - %04d = %04d\n",n,o,zqd);
				kirby[0] = zqd % 10;
				kirby[1] = zqd % 100 / 10;
				kirby[2] = zqd % 1000 / 100;
				kirby[3] = zqd / 1000;
				n = 0;
				o = 0;
				qsort(kirby,4,4,comp);
				for (int i = 0;i < 4;i++){
					o += pow(10,i) * kirby[i];
					n += pow(10,i) * kirby[3 - i];
				}
			}
		}
		return 0;
	}