bzoj3931: [CQOI2015]网络吞吐量(spfa+网络流)

3931: [CQOI2015]网络吞吐量

题目：传送门

 

题解：

　　现在有点难受....跳了一个多钟...菜啊...

       题意都把做法一起给了....最短路+网路流啊。

　　不想说话...记得开long long 

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<algorithm>
#include<queue>
#define qread(x)x=read();
using namespace std;
typedef long long LL;
const LL INF=(1LL<<42);
inline int read()
{
    int f=1,x=0;char ch;
    while(ch<'0' || ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0' && ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return f*x;    
}
struct edge
{
    int x,y,next;LL d;
}e[222222];int last1[222222],len1;
void ins1(int x,int y,LL d)
{
    len1++;
    e[len1].x=x;e[len1].y=y;e[len1].d=d;
    e[len1].next=last1[x];last1[x]=len1;
}
struct node
{
    int x,y,next,other;LL d;
}a[222222];int last[222222],len;
void ins(int x,int y,LL d)
{
    int k1,k2;
    len++;k1=len;
    a[len].x=x;a[len].y=y;a[len].d=d;
    a[len].next=last[x];last[x]=len;
    
    len++;k2=len;
    a[len].x=y;a[len].y=x;a[len].d=0;
    a[len].next=last[y];last[y]=len;
    
    a[k1].other=k2;
    a[k2].other=k1;
}
int n,m;
int st,ed,head,tail;
int list[222222],h[222222];
bool bt_h()
{
    memset(h,0,sizeof(h));h[st]=1;
    list[1]=st;head=1;tail=2;
    while(head!=tail)
    {
        int x=list[head];
        for(int k=last[x];k;k=a[k].next)
        {
            int y=a[k].y;
            if(h[y]==0 && a[k].d>0)
            {
                h[y]=h[x]+1;
                list[tail++]=y;
            }
        }
        head++;
    }
    if(h[ed]>0)return true;
    return false;
}
LL find_flow(int x,LL flow)
{
    if(x==ed)return flow;
    LL s=0,t;
    for(int k=last[x];k;k=a[k].next)
    {
        int y=a[k].y;
        if(h[y]==(h[x]+1) && a[k].d>0 && flow>s)
        {
            t=find_flow(y,min(a[k].d,flow-s));
            s+=t;
            a[k].d-=t;a[a[k].other].d+=t;
        }
    }
    if(s==0)h[x]=0;
    return s;
}
LL dd[222222];
bool v[222222];
void spfa()
{
    for(int i=0;i<=n;i++)dd[i]=INF;
    memset(v,true,sizeof(v));
    memset(list,0,sizeof(list));
    list[1]=st;dd[st]=0;head=1;tail=2;
    while(head!=tail)
    {
        int x=list[head];
        for(int k=last1[x];k;k=e[k].next)
        {
            int y=e[k].y;
            if(dd[y]>dd[x]+e[k].d)
            {
                //printf("%d %d\n",x,y);
                dd[y]=dd[x]+e[k].d;
                if(v[y]==true)
                {
                    v[y]=false;
                    list[tail]=y;tail++;if(tail==n+1)tail=1;
                }
            }
        }
        list[head]=0;
        head++;if(head==n+1)head=1;
        v[x]=true;
    }
}
int main()
{
    //freopen("network.in","r",stdin);
    //freopen("network.out","w",stdout);
    qread(n);qread(m);
    len1=0;memset(last1,0,sizeof(last));
    len=0;memset(last,0,sizeof(last));
    memset(list,0,sizeof(list));
    st=1;ed=n*2;
    for(int i=1;i<=m;i++)
    {
        int x,y;LL d;
        qread(x);qread(y);scanf("%lld",&d);
        ins1(x,y,d);
        ins1(y,x,d);
        //printf("%d %d %lld\n",x,y,d);
    }
    spfa();
    memset(list,0,sizeof(list));
    for(int i=1;i<=n;i++)
    {
        LL x;scanf("%lld",&x);
        if(i!=1 && i!=n)
        {
            ins(i,i+n,x);
            //printf("%d %d\n",i,i+n);
        }
    }
    ins(st,1+n,INF);
    ins(n,ed,INF);
    for(int i=1;i<=n;i++)
    {
        for(int k=last1[i];k;k=e[k].next)
        {    
            int y=e[k].y;
            if(dd[i]+e[k].d==dd[y])
            {
                ins(i+n,y,INF);
            }
        }
    }
    LL ans=0;
    while(bt_h())
        ans+=find_flow(st,INF);
    printf("%lld\n",ans);
    return 0;
}