网络流24题12

状压 + spfa

https://loj.ac/problem/6009

#include <iostream>
#include <cstring>
#include <stdio.h>
#include <queue>
using namespace std;
const int maxn = 109;
struct CC{
    int b1,b2,f1,f2,w;
}cc[maxn];
int n,m;
int dis[1<<20];
int vis[1<<20];
int spfa(int S,int T){
    memset(dis,0x3f,sizeof(dis));
    memset(vis,0,sizeof(vis));
    dis[S] = 0;
    vis[S] = 1;
    queue<int> q;
    q.push(S);
    while(!q.empty()){
        int now = q.front();
        q.pop();
        vis[now] = 0;
        for(int i=1;i<=m;i++){
            if(((~now)&cc[i].b1)==0 && (now&cc[i].b2)==0){
                int v = (now&(~cc[i].f1))|cc[i].f2;
                if(v>=(1<<n) || v<0) continue;
                int w = cc[i].w;
                if(dis[v]>dis[now]+w){
                    dis[v] = dis[now]+w;
                    if(vis[v]==0) {
                        vis[v] = 1;
                        q.push(v);
                    }
                }
            }

        }
    }
    if(dis[T]==0x3f3f3f3f){
        return 0;
    }else{
        return dis[T];
    }
}
int main()
{

    scanf("%d%d",&n,&m);
    for(int i=1;i<=m;i++){
        cc[i] = (CC){0,0,0,0,0};
        int w;
        char str1[30],str2[30];
        scanf("%d%s%s",&w,str1,str2);
        cc[i].w = w;
        for(int j=0;j<n;j++){
            if(str1[j]=='-'){
                cc[i].b2|=(1<<j);
            }else if(str1[j]=='+'){
                cc[i].b1|=(1<<j);
            }
            if(str2[j]=='-'){
                cc[i].f1|=(1<<j);
            }else if(str2[j]=='+'){
                cc[i].f2|=(1<<j);
            }
        }
    }
    int ans = spfa((1<<n)-1,0);
    printf("%d\n",ans);
    return 0;
}