3931: [CQOI2015]网络吞吐量 最短路+最大流

。。题意说的很清楚了，先求最短路径图再拆点网络流。
居然没被long long坑，1A赞。

#include<iostream>#include<cstdio>#include<queue>#include<cstring>#define inf 1e18#define ll long long #define pa pair<ll,int>using namespace std;int n,m,cnt,T;int v[100005],u[100005],w[100005];int next[500005],list[500005];int head[1005], cur[1005],q[1005];ll dis[1005],key[500005];bool vis[1005];priority_queue<pa,vector<pa>,greater<pa> > heap;inline int read(){    int a=0,f=1; char c=getchar();    while (c<'0'||c>'9') {if (c=='-') f=-1; c=getchar();}    while (c>='0'&&c<='9') {a=a*10+c-'0'; c=getchar();}    return a*f;}inline void insert(int x,int y,ll z){    next[++cnt]=head[x];    head[x]=cnt;    list[cnt]=y;    key[cnt]=z;}inline void dijkstra(){    for (int i=1;i<=n;i++) dis[i]=inf;    dis[1]=0;    heap.push(make_pair(0,1));    while (!heap.empty())    {        int x=heap.top().second; heap.pop();        if (vis[x]) continue; vis[x]=1;        for (int i=head[x];i;i=next[i])            if (dis[list[i]]>dis[x]+key[i])            {                dis[list[i]]=dis[x]+key[i];                heap.push(make_pair(dis[list[i]],list[i]));            }    }}inline bool BFS(){    for (int i=1;i<=T;i++) dis[i]=-1;    dis[1]=1; q[1]=1;    int t=0,w=1,x;    while (t<w)    {        x=q[++t];        for (int i=head[x];i;i=next[i])            if (key[i]&&dis[list[i]]==-1)                dis[list[i]]=dis[x]+1,q[++w]=list[i];    }    return dis[T]!=-1;}ll find(int x,ll flow){    if (x==T) return flow;    ll w,used=0;    for (int i=cur[x];i;i=next[i])        if (key[i]&&dis[list[i]]==dis[x]+1)        {            w=find(list[i],min(key[i],flow-used));            key[i]-=w; key[i^1]+=w; used+=w;            if (used==flow) return used;        }    if (!used) dis[x]=-1;    return used;}inline ll dinic(){    ll tmp=0;    while (BFS())    {        for (int i=1;i<=T;i++) cur[i]=head[i];        tmp+=find(1,inf);    }    return tmp;}int main(){    n=read(); m=read();    for (int i=1;i<=m;i++)    {        u[i]=read(),v[i]=read(),w[i]=read();        insert(u[i],v[i],w[i]); insert(v[i],u[i],w[i]);    }    dijkstra();    cnt=1; T=2*n;    memset(head,0,sizeof(head));    for (int i=1;i<=m;i++)    {        if (dis[u[i]]+w[i]==dis[v[i]])             insert(u[i]+n,v[i],inf),insert(v[i],u[i]+n,0);        if (dis[v[i]]+w[i]==dis[u[i]])            insert(v[i]+n,u[i],inf),insert(u[i],v[i]+n,0);    }    for (int i=1;i<=n;i++)    {        int c=read();        if (i==1||i==n) insert(i,i+n,inf),insert(i+n,i,0);        else insert(i,i+n,c),insert(i+n,i,0);    }    cout << dinic() << endl;    return 0;}