bzoj1061 [Noi2008]志愿者招募

//It is made by wfj_2048~
#include <algorithm>
#include <iostream>
#include <complex>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <vector>
#include <cmath>
#include <queue>
#include <stack>
#include <map>
#include <set>
#define inf (1<<29)
#define il inline
#define RG register
#define ll long long
#define File(s) freopen(s".in","r",stdin),freopen(s".out","w",stdout)

using namespace std;

struct edge{ int nt,to,flow,cap,cost; }g[30010];


queue <int> Q;
int head[1010],dis[1010],flow[1010],fa[1010],p[1010],a[1010],n,m,S,T,num=1,cost;

il int gi(){
    RG int x=0,q=1; RG char ch=getchar(); while ((ch<‘0‘ || ch>‘9‘) && ch!=‘-‘) ch=getchar();
    if (ch==‘-‘) q=-1,ch=getchar(); while (ch>=‘0‘ && ch<=‘9‘) x=x*10+ch-48,ch=getchar(); return q*x;
}

il void insert(RG int from,RG int to,RG int cap,RG int cost){ g[++num]=(edge){head[from],to,0,cap,cost},head[from]=num; }

il int bfs(RG int S,RG int T){
    for (RG int i=1;i<=n+3;++i) dis[i]=inf;
    Q.push(S),flow[S]=inf,dis[S]=0;
    while (!Q.empty()){
    RG int x=Q.front(),v; Q.pop();
    for (RG int i=head[x];i;i=g[i].nt){
        v=g[i].to;
        if (dis[v]>dis[x]+g[i].cost && g[i].cap>g[i].flow){
        flow[v]=min(flow[x],g[i].cap-g[i].flow);
        dis[v]=dis[x]+g[i].cost; fa[v]=x,p[v]=i,Q.push(v);
        }
    }
    }
    if (dis[T]==inf) return 0; cost+=flow[T]*dis[T];
    for (RG int x=T;x!=S;x=fa[x]) g[p[x]].flow+=flow[T],g[p[x]^1].flow-=flow[T];
    return 1;
}

il int mcmf(RG int S,RG int T){ cost=0; while (bfs(S,T)); return cost; }

il void work(){
    n=gi(),m=gi(); S=n+2,T=n+3; insert(S,1,inf,0),insert(1,S,0,0);
    for (RG int i=1;i<=n;++i) a[i]=gi(),insert(i,i+1,inf-a[i],0),insert(i+1,i,0,0);
    for (RG int i=1;i<=m;++i){
    RG int s=gi(),t=gi(),c=gi();
    insert(s,t+1,inf,c),insert(t+1,s,0,-c);
    }
    insert(n+1,T,inf,0),insert(T,n+1,0,0);
    printf("%d\n",mcmf(S,T)); return;
}

int main(){
    File("volunteer");
    work();
    return 0;
}