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 }