POJ 2516 Minimum Cost(最小费用最大流)

题目链接

这个题目，建图我是按

源点->(有流量无费用)->人->(无穷的流量有费用)->仓库->(有流量无费用)->汇点

建图没弄好wa了一次。剩下就是模版了。。

  1 #include <cstdio>
  2 #include <cstring>
  3 #include <cmath>
  4 #include <queue>
  5 using namespace std;
  6 #define INF 0x7fffffff
  7 
  8 int pd[51][51];
  9 int im[51][51];
 10 int cc[51][51][51];
 11 
 12 int low[1001],path[1001];
 13 int first[1001],in[1001],dis[1001];
 14 int str,end,t;
 15 struct node
 16 {
 17     int u,v,w,cost,re,next;
 18 }edge[101*101];
 19 int sp,cf;
 20 void CL()
 21 {
 22     t = 1;
 23     memset(first,-1,sizeof(first));
 24 }
 25 void add(int u,int v,int w,int cost)
 26 {
 27     edge[t].u = u;
 28     edge[t].v = v;
 29     edge[t].w = w;
 30     edge[t].cost = cost;
 31     edge[t].re = t+1;
 32     edge[t].next = first[u];
 33     first[u] = t ++;
 34 
 35     edge[t].u = v;
 36     edge[t].v = u;
 37     edge[t].w = 0;
 38     edge[t].cost = -cost;
 39     edge[t].re = t-1;
 40     edge[t].next = first[v];
 41     first[v] = t ++;
 42 }
 43 int bfs()
 44 {
 45     int u,i,v;
 46     memset(path,-1,sizeof(path));
 47     for(i = 0;i <= end;i ++)
 48     {
 49         dis[i] = INF;
 50         in[i] = 0;
 51     }
 52     queue<int>que;
 53     que.push(str);
 54     dis[str] = 0;
 55     in[str] = 1;
 56     low[str] = INF;
 57     while(!que.empty())
 58     {
 59         u = que.front();
 60         in[u] = 0;
 61         que.pop();
 62         for(i = first[u];i != -1;i = edge[i].next)
 63         {
 64             v = edge[i].v;
 65             if(edge[i].w&&dis[v] > dis[u]+edge[i].cost)
 66             {
 67                 dis[v] = dis[u] + edge[i].cost;
 68                 path[v] = i;
 69                 low[v] = low[u] < edge[i].w ? low[u]:edge[i].w;
 70                 if(!in[v])
 71                 {
 72                     que.push(v);
 73                     in[v] = 1;
 74                 }
 75             }
 76         }
 77     }
 78     if(path[end] == -1)
 79     return -1;
 80     else
 81     return low[end];
 82 
 83 }
 84 void mcmf()
 85 {
 86     int res,temp,now;
 87     while((res = bfs()) != -1)
 88     {
 89         now = end;
 90         cf += res;
 91         while(now != str)
 92         {
 93             temp = path[now];
 94             edge[temp].w -= res;
 95             edge[edge[temp].re].w += res;
 96             sp += res*edge[temp].cost;
 97             now = edge[temp].u;
 98         }
 99     }
100 }
101 int main()
102 {
103     int n,m,k,u,ans,sum,i,j;
104     while(scanf("%d%d%d",&n,&m,&k)!=EOF)
105     {
106         if(!n&&!m&&!k) break;
107         for(i = 1;i <= n;i ++)
108         {
109             for(j = 1;j <= k;j ++)
110             scanf("%d",&pd[i][j]);
111         }
112         for(i = 1;i <= m;i ++)
113         {
114             for(j = 1;j <= k;j ++)
115             scanf("%d",&im[i][j]);
116         }
117         for(i = 1;i <= k;i ++)
118         {
119             for(j = 1;j <= n;j ++)
120             {
121                 for(u = 1;u <= m;u ++)
122                 scanf("%d",&cc[i][j][u]);
123             }
124         }
125         str = 0;
126         end = n+m+1;
127         ans = 0;
128         for(i = 1;i <= k;i ++)
129         {
130             CL();
131             sum = 0;
132             for(j = 1;j <= n;j ++)
133             {
134                 add(str,j,pd[j][i],0);
135                 sum += pd[j][i];
136             }
137             for(j = 1;j <= m;j ++)
138             add(n+j,end,im[j][i],0);
139             for(j = 1;j <= n;j ++)
140             {
141                 for(u = 1;u <= m;u ++)
142                 add(j,n+u,INF,cc[i][j][u]);
143             }
144             sp = cf = 0;
145             mcmf();
146             if(cf < sum) break;
147             ans += sp;
148         }
149         if(i == k+1)
150         printf("%d\n",ans);
151         else
152         printf("-1\n");
153     }
154     return 0;
155 }

 

posted @ 2013-02-27 09:40  Naix_x  阅读(182)  评论(0)  编辑  收藏  举报