hdu 3572 Task Schedule (Dinic模板)

Problem Description

Our geometry princess XMM has stoped her study in computational geometry to concentrate on her newly opened factory. Her factory has introduced M new machines in order to process the coming N tasks. For the i-th task, the factory has to start processing it at or after day Si, process it for Pi days, and finish the task before or at day Ei. A machine can only work on one task at a time, and each task can be processed by at most one machine at a time. However, a task can be interrupted and processed on different machines on different days.
Now she wonders whether he has a feasible schedule to finish all the tasks in time. She turns to you for help.

Input

On the first line comes an integer T(T<=20), indicating the number of test cases.
You are given two integer N(N<=500) and M(M<=200) on the first line of each test case. Then on each of next N lines are three integers Pi, Si and Ei (1<=Pi, Si, Ei<=500), which have the meaning described in the description. It is guaranteed that in a feasible schedule every task that can be finished will be done before or at its end day.

Output

For each test case, print “Case x: ” first, where x is the case number. If there exists a feasible schedule to finish all the tasks, print “Yes”, otherwise print “No”.
Print a blank line after each test case.

Sample Input

4 3

1 3 5

1 1 4

2 3 7

3 5 9

2 2

2 1 3

1 2 2

Sample Output

Case 1: Yes

Case 2: Yes

给N个任务，M台机器。每个任务有最早才能开始做的时间S，deadline E，和持续工作的时间P。每个任务可以分段进行,但是在同一时刻,一台机器最多只能执行一个任务. 问存不存在可行的工作时间。

由于时间<=500且每个任务都能断断续续的执行,那么我们把每一天时间作为一个节点来用网络流解决该题.
建图: 源点s(编号0), 时间1-500天编号为1到500, N个任务编号为500+1 到500+N, 汇点t(编号501+N).
源点s到每个任务i有边(s, i, Pi)
每一天到汇点有边(j, t, M) (其实这里的每一天不一定真要从1到500,只需要取那些被每个任务覆盖的每一天即可)
如果任务i能在第j天进行,那么有边(i, j, 1) 注意由于一个任务在一天最多只有1台机器执行,所以该边容量为1,不能为INF或M哦.
最后看最大流是否 == 所有任务所需要的总天数.

 #include <bits/stdc++.h>

 using namespace std;

 const int maxn = ;

 const int inf = 0x3f3f3f3f;

 struct Edge

 {

     int from,to,cap,flow;

     Edge (int f,int t,int c,int fl)

     {

         from=f,to=t,cap=c,flow=fl;

     }

 };

 struct Dinic

 {

     int n,m,s,t;

     vector <Edge> edge;

     vector <int> G[maxn];//存图

     bool vis[maxn];//标记每点是否vis过

     int cur[maxn];//当前弧优化

     int dep[maxn];//标记深度

     void init(int n,int s,int t)//初始化

     {

         this->n=n;this->s=s;this->t=t;

         edge.clear();

         for (int i=;i<n;++i) G[i].clear();

     }

     void addedge (int from,int to,int cap)//加边,单向边

     {

         edge.push_back(Edge(from,to,cap,));

         edge.push_back(Edge(to,from,,));

         m=edge.size();

         G[from].push_back(m-);

         G[to].push_back(m-);

     }

     bool bfs ()

     {

         queue<int> q;

         while (!q.empty()) q.pop();

         memset(vis,false,sizeof vis);

         vis[s]=true;

         dep[s]=;

         q.push(s);

         while (!q.empty()){

             int u=q.front();

             //printf("%d\n",u);

             q.pop();

             for (int i=;i<G[u].size();++i){

                 Edge e=edge[G[u][i]];

                 int v=e.to;

                 if (!vis[v]&&e.cap>e.flow){

                     vis[v]=true;

                     dep[v]=dep[u]+;

                     q.push(v);

                 }

             }

         }

         return vis[t];

     }

     int dfs (int x,int mi)

     {

         if (x==t||mi==) return mi;

         int flow=,f;

         for (int &i=cur[x];i<G[x].size();++i){

             Edge &e=edge[G[x][i]];

             int y=e.to;

             if (dep[y]==dep[x]+&&(f=dfs(y,min(mi,e.cap-e.flow)))>){

                 e.flow+=f;

                 edge[G[x][i]^].flow-=f;

                 flow+=f;

                 mi-=f;

                 if (mi==) break;

             }

         }

         return flow;

     }

     int max_flow ()

     {

         int ans = ;

         while (bfs()){

             memset(cur,,sizeof cur);

             ans+=dfs(s,inf);

         }

         return ans;

     }

 }dinic;

 int full_flow;

 int main()

 {

     int casee = ;

     //freopen("de.txt","r",stdin);

     int T;scanf("%d",&T);

     while (T--){

         int n,m;

         full_flow = ;

         scanf("%d%d",&n,&m);

         int src = ,dst = ++n;

         dinic.init(++n,src,dst);

         bool vis[maxn];

         memset(vis,false,sizeof vis);

         for (int i=;i<=n;++i){

             int p,s,e;

             scanf("%d%d%d",&p,&s,&e);

             full_flow+=p;

             dinic.addedge(src,i+,p);

             for (int j=s;j<=e;++j){

                 vis[j]=true;

                 dinic.addedge(i+,j,);

             }

         }

         for (int i=;i<maxn;++i){

             if (vis[i])

                 dinic.addedge(i,dst,m);

         }

         printf("Case %d: ",++casee);

         if (dinic.max_flow()==full_flow){//dinic.max_flow()只能跑一遍

             printf("Yes\n\n");

         }

         else

             printf("No\n\n");

     }

     return ;

 }

巴特西

hdu 3572 Task Schedule (Dinic模板)

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