https://vjudge.net/problem/UVA-658
Ideas: the state of each bug represented in binary, each state as the point, each of the transformation process as the edge, since the relatively small patch, may not be built on the edge found in FIG direct violence vans, dijkstra line;
#include<iostream> #include<iomanip> #include<cstring> #include<sstream> #include<algorithm> #include<cstdio> #include<cmath> #include<stdlib.h> #include<string> #include<queue> #include<vector> #include<map> #include<set> #include<stack> //#include<bits/stdc++.h> #define _for(i,a,b) for(int i=a;i<=b;i++) using namespace std; typedef long long ll; const int mod =1e6+7; double esp=1e-6; int INF =0x3f3f3f3f; //const int inf = 1<<28; const int MAXN=200000+10; const int inf=0x3f3f3f3f; char be[110][25],af[110][25]; int vis[1<<20],d[1<<20],t[110],n,m; struct node { int bug,dist; bool operator < (const node &p)const { return dist>p.dist; } }; int dijkstar() { for(int i=0;i<(1<<n);i++) { d[i]=INF; vis[i]=0; } priority_queue<node> Q; Q.push((node){(1<<n)-1,0}); d[(1<<n)-1]=0; while(!Q.empty()) { node x=Q.top(); Q.pop(); if(x.bug==0)return x.dist; if(vis[x.bug])continue; vis[x.bug]=1; for(int i=0;i<m;i++) { bool f=1; for(int j=0;j<n;j++) { if(be[i][j]=='-'&&(x.bug&(1<<j))){f=0;break;} if(be[i][j]=='+'&&!(x.bug&(1<<j))){f=0;break;} } if(!f)continue; node next; next.bug=x.bug; next.dist=x.dist+t[i]; for(int j=0;j<n;j++) { if(af[i][j]=='+')next.bug |= (1<<j); if(af[i][j]=='-')next.bug &= ~(1<<j); } if(next.dist<d[next.bug]) { d[next.bug]=next.dist; Q.push(next); } } } return -1; } int main() { int Case=0; while(scanf("%d%d",&n,&m)&&n&&m) { for(int i=0;i<m;i++) { scanf("%d%s%s",&t[i],be[i],af[i]); } int ans=dijkstar(); printf("Product %d\n",++Case); if(ans<0)printf("Bugs cannot be fixed.\n\n"); else printf("Fastest sequence takes %d seconds.\n\n",ans); } return 0; }