BZOJ 3931 Dijkstra+网络流

思路：
（我能说按照题意模拟么）

用long long
inf 要开大…….

//By SiriusRen#include <queue>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;#define int long long#define N 1017#define M 999999#define inf 0x3f3f3f3f3f3f3f3fllint n,m,xx[M],yy[M],zz[M],first[N],next[M],v[M],w[M],tot,dis[N],vis[N],tmp,ans;struct Node{int wei,now;}jy;bool operator < (Node a,Node b){return a.wei>b.wei;}void Add(int x,int y,int z){w[tot]=z,v[tot]=y,next[tot]=first[x],first[x]=tot++;}struct Dijkstra{    void add(int x,int y,int z){Add(x,y,z),Add(y,x,z);}    void solve(){        memset(dis,0x3f,sizeof(dis)),dis[1]=0;        priority_queue<Node>pq;jy.now=1,pq.push(jy);        while(!pq.empty()){            Node t=pq.top();pq.pop();            if(vis[t.now])continue;            vis[t.now]=1;            for(int i=first[t.now];~i;i=next[i])                if(dis[v[i]]>dis[t.now]+w[i])                    dis[v[i]]=dis[t.now]+w[i],                    jy.now=v[i],jy.wei=dis[v[i]],pq.push(jy);        }    }}dijk;struct Dinic{    void add(int x,int y,int z){Add(x,y,z),Add(y,x,0);}    bool tell(){        memset(vis,-1,sizeof(vis)),vis[1]=0;        queue<int>q;q.push(1);        while(!q.empty()){            int t=q.front();q.pop();            for(int i=first[t];~i;i=next[i])                if(!~vis[v[i]]&&w[i])                    vis[v[i]]=vis[t]+1,q.push(v[i]);        }return ~vis[2*n];    }    int zeng(int x,int y){        if(x==2*n)return y;        int r=0;        for(int i=first[x];~i;i=next[i])            if(vis[v[i]]==vis[x]+1&&w[i]){                int t=zeng(v[i],min(y-r,w[i]));                w[i]-=t,w[i^1]+=t,r+=t;            }        if(!r)vis[x]=-1;        return r;    }    void flow(){        while(tell())while(tmp=zeng(1,inf))ans+=tmp;        printf("%lld\n",ans);    }}dinic;void init(){memset(first,-1,sizeof(first)),tot=0;}signed main(){    init(),scanf("%lld%lld",&n,&m);    for(int i=1;i<=m;i++){        scanf("%lld%lld%lld",&xx[i],&yy[i],&zz[i]);        dijk.add(xx[i],yy[i],zz[i]);    }    dijk.solve(),init();    for(int i=1;i<=m;i++){        if(dis[yy[i]]==dis[xx[i]]+zz[i])dinic.add(xx[i]+n,yy[i],inf);        if(dis[xx[i]]==dis[yy[i]]+zz[i])dinic.add(yy[i]+n,xx[i],inf);    }    for(int i=1;i<=n;i++){        scanf("%lld",&tmp);        if(i!=1&&i!=n)dinic.add(i,i+n,tmp);        else dinic.add(i,i+n,inf);    }    dinic.flow();}