uva 567 Risk bfs

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <queue>
#include <cstring>
using namespace std;
int ma[25][25];
int d[25];
int vis[25];

int fun(int x,int y){
	queue<int> que;
	que.push(x);
	vis[x] = 1;
	d[x] = 0;

	while(1){
		int tm = que.front();
		que.pop();

		for(int i = 1;i <= 20;i++){
			if(ma[tm][i] && !vis[i]){
				if(i == y) {
					return d[tm] + 1;
				}
				else{
					vis[i] = 1;
					d[i] = d[tm]+1;
					que.push(i);
				}
			}
		}
	}
}
int main(){

	int n;
	int q = 1;

	while(cin >> n){
		memset(ma,0,sizeof(ma));

		for(int i = 0;i < n;i++){
			int y;

			cin >> y;
			ma[1][y] = 1;
			ma[y][1] = 1;
		}
		for(int i = 2;i < 20;i++){
			cin >> n;

			for(int j = 0;j < n;j++){
				int y;
				cin >> y;
				ma[i][y] = 1;
				ma[y][i] = 1;
			}
		} 

		int m;
		cin >> m;
		printf("Test Set #%d\n",q++);
		for(int i = 0;i < m;i++){
			int x,y;
			cin >> x >> y;
			memset(vis,0,sizeof(vis));
			memset(d,0,sizeof(d));
			printf("%2d to %2d: %d\n",x,y,fun(x,y));
		}
		cout << endl;

	}
	return 0;
}