ZOJ1244(AC).cpp

#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

void sort(char a[], int n)
{
	int i, j;
	char tmp;

	for(i = 0; i < n - 1; i++){
		for(j = i + 1; j < n; j++){
			if(a[i] > a[j]){
				tmp = a[i];
				a[i] = a[j];
				a[j] = tmp;
			}
		}
	}
}

int find(char a[], int n, int key)
{
	int i;

	for(i = 0; i < n; i++){
		if(a[i] == key){
			return i;
		}
	}

	return -1;
}

int main()
{
	int i;
	int j;
	int n;
	int c;
	int pos;
	char str[1000];
	char a[100];
	char dst;
	char src;

	int casecount;

	casecount = 0;
	while(true){
		c = 0;
		a[c] = 'a';
		c++;
		gets(str);
		sscanf(str, "%d", &n);
		if(n == 0){
			break;
		}else{
			casecount++;
		}

		for(i = 0; i < n; i++){
			gets(str);
			sscanf(str, "%c = %c", &dst, &src);
			pos = find(a, c, src);
			if(pos != -1){
				pos = find(a, c, dst);
				if(pos == -1){
					a[c] = dst;
					c++;
				}
			}else{
				pos = find(a, c, dst);
				if(pos != -1){
					for(j = pos + 1; j < c; j++){
						a[j - 1] = a[j];
					}
					c--;
				}
			}
		}
		sort(a, c);

		printf("Program #%d\n", casecount);
		if(c == 0){
			printf("none");
			printf("\n\n");
		}else{
			for(i = 0; i < c; i++){
				printf("%c ", a[i]);
			}
			printf("\n\n");
		}
	}

	return 0;
}