hdu 2883 kebab 网络流

  1 #include<iostream>
  2 #include<cstdio>
  3 #include<cstring>
  4 #include<cstdlib>
  5 #include<cmath>
  6 #include<algorithm>
  7 #include<queue>
  8 #include<vector>
  9 #define inf 0x7fffffff
 10 using namespace std;
 11 const int maxn=600+10;
 12 const int M = 999999;
 13 
 14 int n,m,from,to;
 15 int d[maxn];
 16 struct node
 17 {
 18     int v,flow;
 19     int next;
 20 }edge[M*2];
 21 int head[maxn],edgenum;
 22 
 23 void add(int u,int v,int flow)
 24 {
 25     edge[edgenum].v=v ;edge[edgenum].flow=flow ;
 26     edge[edgenum].next=head[u];
 27     head[u]=edgenum++;
 28 
 29     edge[edgenum].v=u ;edge[edgenum].flow=0;
 30     edge[edgenum].next=head[v];
 31     head[v]=edgenum++;
 32 }
 33 
 34 int bfs()
 35 {
 36     memset(d,0,sizeof(d));
 37     d[from]=1;
 38     queue<int> Q;
 39     Q.push(from);
 40     while (!Q.empty())
 41     {
 42         int u=Q.front() ;Q.pop() ;
 43         for (int i=head[u] ;i!=-1 ;i=edge[i].next)
 44         {
 45             int v=edge[i].v;
 46             if (!d[v] && edge[i].flow>0)
 47             {
 48                 d[v]=d[u]+1;
 49                 Q.push(v);
 50                 if (v==to) return 1;
 51             }
 52         }
 53     }
 54     return 0;
 55 }
 56 
 57 int dfs(int u,int flow)
 58 {
 59     if (u==to || flow==0) return flow;
 60     int cap=flow;
 61     for (int i=head[u] ;i!=-1 ;i=edge[i].next)
 62     {
 63         int v=edge[i].v;
 64         if (d[v]==d[u]+1 && edge[i].flow>0)
 65         {
 66             int x=dfs(v,min(cap,edge[i].flow));
 67             edge[i].flow -= x;
 68             edge[i^1].flow += x;
 69             cap -= x;
 70             if (cap==0) return flow;
 71         }
 72     }
 73     return flow-cap;
 74 }
 75 
 76 int dinic()
 77 {
 78     int sum=0;
 79     while (bfs()) sum += dfs(from,inf);
 80     return sum;
 81 }
 82 
 83 int main()
 84 {
 85     while (scanf("%d%d",&n,&m)!=EOF)
 86     {
 87         memset(head,-1,sizeof(head));
 88         edgenum=0;
 89         int s[222],q[222],e[222],t[222];
 90         int time[maxn],cnt=1;
 91         memset(time,0,sizeof(time));
 92         int sum=0;
 93         for (int i=1 ;i<=n ;i++)
 94         {
 95             scanf("%d%d%d%d",&s[i],&q[i],&e[i],&t[i]);
 96             sum += q[i]*t[i];
 97             time[cnt++]=s[i];
 98             time[cnt++]=e[i];
 99         }
100         sort(time+1,time+cnt);
101         int c=0;
102         for (int i=1 ;i<cnt ;i++)
103         {
104             if (time[c] != time[i])
105                 time[++c]=time[i];
106         }
107         from=n+c+1;
108         to=from+1;
109         for (int i=1 ;i<=n ;i++)
110             add(from,i,q[i]*t[i]);
111         for (int i=1 ;i<=c ;i++)
112         {
113             add(n+i,to,m*(time[i]-time[i-1]));
114             for (int j=1 ;j<=n ;j++)
115             {
116                 if (s[j]<=time[i-1] && time[i]<=e[j])
117                     add(j,n+i,inf);
118             }
119         }
120         if (sum==dinic()) printf("Yes\n");
121         else printf("No\n");
122     }
123     return 0;
124 }