UVA - 658 It's not a Bug, it's a Feature!

#include<bits/stdc++.h>
using namespace std;

const int maxm = 100;
const int maxn = 20;

int pre[maxm][2],nxt[maxm][2];
int cost[maxm];
int n,m;

int dist[1<<maxn];

typedef pair<int,int> Node;
#define fi first
#define se second

//bitset<20> temp;
#define bug(u)\
temp = u; cout<<#u<<‘=‘<<temp<<endl;
#define cer(x)\
cout<<"dist="<<x<<endl;

const int INF = 0x3f3f3f3f;

void dijkstra()
{
    priority_queue<Node,vector<Node>,greater<Node> > q;
    memset(dist,0x3f,sizeof(int)*(1<<n));
    q.push(Node(0,(1<<n)-1));
    dist[(1<<n)-1] = 0;
    while(q.size()){
        Node x = q.top(); q.pop();
        if(x.se == 0)  { printf("Fastest sequence takes %d seconds.\n",dist[0]); return; }
        if(x.fi != dist[x.se]) continue;
        int u = x.se;
        for(int i = 0; i < m; i++){
            if( (pre[i][0]&u) == u && (pre[i][1]|u) == u){
                int v = (u&nxt[i][0])|nxt[i][1];
                if(dist[v] > dist[u]+cost[i]){
                    dist[v] = dist[u] + cost[i];
                    q.push(Node(dist[v],v));
                }
            }
        }
    }
    puts("Bugs cannot be fixed.");
}



int main()
{
    //freopen("in.txt","r",stdin);
    int kas = 0;
    char s1[maxn+5],s2[maxn+5];
    while(scanf("%d%d",&n,&m),n){
        for(int i = 0; i < m ; i++){
            scanf("%d%s%s",cost+i,s1,s2);
            nxt[i][0] = nxt[i][1] = pre[i][0] = pre[i][1] = 0;
            for(int j = 0; j < n; j++){
                if(s1[j] == ‘+‘) pre[i][1] |= 1<<j;
                if(s1[j] != ‘-‘) pre[i][0] |= 1<<j;
                if(s2[j] == ‘+‘) nxt[i][1] |= 1<<j;
                if(s2[j] != ‘-‘) nxt[i][0] |= 1<<j;
            }
        }
        printf("Product %d\n",++kas);
        dijkstra();
        putchar(‘\n‘);
    }
    return 0;
}