bzoj1061： [Noi2008]志愿者招募

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<queue>
using namespace std;
#define rep(i,s,t) for(int i=s;i<=t;i++)
#define clr(x,c) memset(x,c,sizeof(x))
#define qwq(x) for(edge *o=head[x];o;o=o->next)
int read(){
	int x=0;char c=getchar();
	while(!isdigit(c)) c=getchar();
	while(isdigit(c)) x=x*10+c-‘0‘,c=getchar();
	return x;
}
const int nmax=1005;
const int maxn=10005;
const int inf=0x7f7f7f7f;
struct edge{
	int to,cap,cost;edge *next,*rev;
};
edge es[maxn<<2],*pt=es,*head[nmax],*p[nmax];
void add(int u,int v,int d,int w){
	pt->to=v;pt->cap=d;pt->cost=w;pt->next=head[u];head[u]=pt++;
	pt->to=u;pt->cap=0;pt->cost=-w;pt->next=head[v];head[v]=pt++;
	head[u]->rev=head[v];head[v]->rev=head[u];
}
queue<int>q;
int a[nmax],dis[nmax],ai[nmax],si[maxn],ti[maxn],ci[maxn];
bool inq[nmax];
int mincost(int s,int t){
	int cost=0;
	while(1){
		clr(dis,0x7f);clr(inq,0);inq[s]=1;dis[s]=0;
		a[s]=inf;q.push(s);
		while(!q.empty()){
			int x=q.front();q.pop();inq[x]=0;
			qwq(x) if(o->cap>0&&dis[o->to]>dis[x]+o->cost){
				int to=o->to;dis[to]=dis[x]+o->cost;
				a[to]=min(a[x],o->cap);p[to]=o;
				if(!inq[to]) q.push(to),inq[to]=1;
			}
		}
		if(dis[t]==inf) break;
		cost+=dis[t]*a[t];
		int x=t;
		while(x!=s) p[x]->cap-=a[t],p[x]->rev->cap+=a[t],x=p[x]->rev->to;
	}
	return cost;
}
int main(){
	int n=read(),m=read(),u,v,d,s=0,t=n+2;
	rep(i,1,n) ai[i]=read();
	rep(i,1,m) si[i]=read(),ti[i]=read(),ci[i]=read();
	rep(i,1,n+1) {
		u=ai[i]-ai[i-1];
		if(u>0) add(s,i,u,0);
		else add(i,t,-u,0);
	}
	rep(i,1,m) add(si[i],ti[i]+1,inf,ci[i]);
	rep(i,1,n) add(i+1,i,inf,0);
	printf("%d\n",mincost(s,t));
	return 0;
}