POJ3762 The Bonus Salary! （费用流+离散化）

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <queue>
#include <cmath>
#include <vector>
#include <algorithm>
#include <limits.h>
using namespace std;
#define inf 1e8
#define maxn 4005
#define maxm 100005
int head[maxn],eid;
int dis[maxn];
bool vis[maxn];
int a[maxn];
int pre[maxn];
struct node
{
    int u,v,cap,next,cost;
}eg[maxm];
void add(int u,int v,int cap,int cost)
{
    eg[eid].u=u;
    eg[eid].v=v;
    eg[eid].cap=cap;
    eg[eid].next=head[u];
    eg[eid].cost=cost;
    head[u]=eid++;
    eg[eid].u=v;
    eg[eid].v=u;
    eg[eid].cap=0;
    eg[eid].next=head[v];
    eg[eid].cost=-cost;
    head[v]=eid++;
}
bool spfa(int s,int t,int &flow,int &cost)
{
    memset(vis,false,sizeof(vis));
    for(int i=0;i<maxn;i++)
        dis[i]=inf;
    dis[s]=0;
    vis[s]=true;
    pre[s]=0;
    a[s]=inf;
    queue<int>q;
    q.push(s);
    while(!q.empty())
    {
        int u=q.front();
        q.pop();
        vis[u]=false;
        for(int i=head[u];i!=-1;i=eg[i].next)
        {
            if(eg[i].cap&&dis[eg[i].v]>dis[u]+eg[i].cost)
            {
                dis[eg[i].v]=dis[u]+eg[i].cost;
                pre[eg[i].v]=i;
                a[eg[i].v]=min(a[u],eg[i].cap);
                if(!vis[eg[i].v])
                {
                    q.push(eg[i].v);
                    vis[eg[i].v]=true;
                }
            }
        }
    }
    if(dis[t]==inf) return false;
    flow+=a[t];
    cost+=dis[t]*a[t];
    int u=t;
    while(u!=s)
    {
        eg[pre[u]].cap-=a[t];
        eg[pre[u]^1].cap+=a[t];
        u=eg[pre[u]].u;
    }
    return true;
}
int mincost(int s,int t)
{
    int flow=0,cost=0;
    while(spfa(s,t,flow,cost));
    return cost;
}
void init()
{
    memset(head,-1,sizeof(head));
    eid=0;
}
int t1[maxn],t2[maxn],t3[maxn*2],t4[maxn*2],v[maxn];
int main()
{
    //freopen("in.txt","r",stdin);
    int n,m,x,y,z;
    while(~scanf("%d%d",&n,&m))
    {
        init();
        for(int i=0;i<n;i++)
        {
            scanf("%2d:%2d:%2d",&x,&y,&z);
            t1[i]=x*10000+y*100+z;
            t3[i*2]=t1[i];
            scanf("%2d:%2d:%2d",&x,&y,&z);
            t2[i]=x*10000+y*100+z;
            t3[i*2+1]=t2[i];
            scanf("%d",&v[i]);
        }
        sort(t3,t3+n*2);
        int tot=1;
        for(int i=0;i<n*2;i++)
        {
            t4[tot++]=t3[i];
            while(i+1<n*2&&t3[i+1]==t3[i]) i++;
        }
        if(t4[tot-1]==t4[tot-2]) tot--;
        for(int i=0;i<n;i++)
        {
            int flag=0;
            for(int j=1;j<tot;j++)
            {
                if(t1[i]==t4[j])
                {
                    t1[i]=j;
                    flag++;
                }
                if(t2[i]==t4[j])
                {
                    t2[i]=j;
                    flag++;
                }
                if(flag==2) break;
            }
        }
        for(int i=0;i<tot;i++)
            add(i,i+1,m,0);
        for(int i=0;i<n;i++)
            add(t1[i],t2[i],1,-v[i]);
        printf("%d\n",-mincost(0,tot));
    }
    return 0;
}