洛谷P3357 最长k可重线段集问题(费用流)

4 2
1 2 7 3
6 5 8 3
7 8 10 5
9 6 13 9 

17

#include<cstdio>
#include<cstring>
#include<queue>
#include<algorithm>
#include<vector>
#include<cmath>
#define int long long 
#define AddEdge(x,y,z,f) add_edge(x,y,z,f),add_edge(y,x,-z,0)
using namespace std;
const int MAXN=1e5+10;
const int INF=1e8+10;
inline int read()
{
    char c=getchar();int x=0,f=1;
    while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
    while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
    return x*f;
}
int N,K,S,T;
int anscost=0;
struct node
{
    int u,v,w,f,nxt;
}edge[MAXN];
int head[MAXN],num=2;
inline void add_edge(int x,int y,int z,int f)
{
    edge[num].u=x;
    edge[num].v=y;
    edge[num].w=z;
    edge[num].f=f;
    edge[num].nxt=head[x];
    head[x]=num++;
}
int Pre[MAXN],vis[MAXN],dis[MAXN];
bool SPFA()
{
    queue<int>q;
    memset(dis,0x3f,sizeof(dis));
    memset(vis,0,sizeof(vis));
    dis[S]=0;
    q.push(S);
    while(q.size()!=0)
    {
        int p=q.front();q.pop();
        vis[p]=0;
        for(int i=head[p];i!=-1;i=edge[i].nxt)
        {
            if(dis[edge[i].v]>dis[p]+edge[i].w&&edge[i].f)
            {
                dis[edge[i].v]=dis[p]+edge[i].w;
                Pre[edge[i].v]=i;
                if(!vis[edge[i].v])
                    vis[edge[i].v]=1,q.push(edge[i].v);
            }
        }
    }
    return dis[T]<=INF;
}
void f()
{
    int nowflow=INF;
    for(int now=T;now!=S;now=edge[Pre[now]].u)
        nowflow=min(nowflow,edge[Pre[now]].f);
    for(int now=T;now!=S;now=edge[Pre[now]].u)
        edge[Pre[now]].f-=nowflow,
        edge[Pre[now]^1].f+=nowflow;
    anscost+=nowflow*dis[T];
}
void MCMF()
{
    int ans=0;
    while(SPFA())
        f();
    printf("%lld\n",-anscost);
}
int L[MAXN],R[MAXN],date[MAXN],tot=0;
struct Point
{
    int xx1,yy1,xx2,yy2,L;
}P[MAXN];
double GetL(int n)
{
    return floor((double)sqrt((P[n].xx1-P[n].xx2)*(P[n].xx1-P[n].xx2) + (P[n].yy1-P[n].yy2)*(P[n].yy1-P[n].yy2)));
}
main()
{
    #ifdef WIN32
    freopen("a.in","r",stdin);
    #else
    #endif
    memset(head,-1,sizeof(head));
    N=read();K=read();
    for(int i=1;i<=N;i++)
    {
        P[i].xx1=read(),P[i].yy1=read(),P[i].xx2=read(),P[i].yy2=read();
        if(P[i].xx1>P[i].xx2) 
            swap(P[i].xx1,P[i].xx2),
            swap(P[i].yy1,P[i].yy2);
        P[i].L=GetL(i);
        P[i].xx1*=2;
        P[i].xx2*=2;
        if(P[i].xx1==P[i].xx2) P[i].xx1--;
        else P[i].xx1++;
        date[++tot]=P[i].xx1,date[++tot]=P[i].xx2;
    }

    sort(date+1,date+tot+1);
    int num=unique(date+1,date+tot+1)-date-1;
    for(int i=1;i<=num-1;i++)
        AddEdge(i,i+1,0,INF);
    for(int i=1;i<=N;i++)
    {
        P[i].xx1=lower_bound(date+1,date+num+1,P[i].xx1)-date;
        
        P[i].xx2=lower_bound(date+1,date+num+1,P[i].xx2)-date;
        
        AddEdge(P[i].xx1,P[i].xx2,-P[i].L,1);
    }
    S=0,T=num*2;
    AddEdge(S,1,0,K);
    AddEdge(num,T,0,K);
    MCMF();
    return 0;
}