网络流-区间K覆盖

模板题目

Code

---

#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
using namespace std;

const int inf=1e10;
const int N=2e3;

struct fuck{int id,op,v,l,r;}tmp[N],later[N];
struct node{int y,n,v,w;}e[N];
int lin[N],d[N],incf[N],pre[N],v[N],len=1,cnt=0,tot=0,TOT,S,T,n,k,l,r,val[N],ans;

void read(int x,int y,int v,int w)
{e[++len].y=y,e[len].v=v,e[len].w=w,e[len].n=lin[x],lin[x]=len;}

void add(int x,int y,int v,int w)
{read(x,y,v,w),read(y,x,0,-w);}

bool cmp(fuck x,fuck y){return x.v<y.v;}

void init(){
	len=1,tot=0,cnt=0,ans=0;
	memset(tmp,0,sizeof(tmp));
	memset(later,0,sizeof(later));
	memset(e,0,sizeof(e));
	memset(lin,0,sizeof(lin));
}

bool SPFA(int S,int T){
	memset(v,0,sizeof(v));
	memset(d,0xcf,sizeof(d));
	memset(incf,0,sizeof(incf));//注意清零
	queue<int> q;
	q.push(S),d[S]=0,incf[S]=inf,v[S]=1;
	while(q.size()){
		int x=q.front();q.pop();v[x]=0;
		for(int i=lin[x];i;i=e[i].n){
			int y=e[i].y;
			if(e[i].v<=0)continue;
			if(d[y]<d[x]+e[i].w){
				pre[y]=i;
				d[y]=d[x]+e[i].w;
				incf[y]=min(incf[x],e[i].v);
				if(!v[y])v[y]=1,q.push(y);
			}
		}
	}
	return incf[T]>0;
}
void upd(int S,int T){
	int x=T;
	while(x!=S){
		int i=pre[x];
		e[i].v-=incf[T];
		e[i^1].v+=incf[T];
		x=e[i^1].y;
	}
	ans+=d[T]*incf[T];
}
int main()
{
	scanf("%d",&TOT);
	while(TOT--){
		init();
		scanf("%d%d",&n,&k);
		
		rep(i,1,n){
			scanf("%d%d%d",&l,&r,&val[i]);
			tmp[++cnt].id=i,tmp[cnt].op=0,tmp[cnt].v=l;
			tmp[++cnt].id=i,tmp[cnt].op=1,tmp[cnt].v=r;
		}
		sort(tmp+1,tmp+cnt+1,cmp);
		rep(i,1,cnt){
			if(tmp[i].v!=tmp[i-1].v)tot++;
			if(tmp[i].op==0)later[tmp[i].id].l=tot;
			else later[tmp[i].id].r=tot;
		}
		rep(i,1,n)add(later[i].l,later[i].r,1,val[i]);//手动离散化
		
		S=0,T=tot+1;
		rep(i,1,tot)add(i,i+1,k,0);add(0,1,k,0);
		while(SPFA(S,T))upd(S,T);
		printf("%d\n",ans);
	}
	return 0;
}