P4015 运输问题 最大/最小费用最大流

P4015 运输问题

 #include <bits/stdc++.h>

 using namespace std;

 const int maxn = , inf = 0x3f3f3f3f;

 struct Edge {

     int from, to, cap, flow, cost;

 };

 struct MCMF {

     int n, m, s, t;

     vector<Edge> edges;

     vector<int> G[maxn];

     int inq[maxn];

     int d[maxn];

     int p[maxn];

     int a[maxn];

     void init(int n) {

         this->n = n;

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

         edges.clear();

     }

     void AddEdge(int from, int to, int cap, int cost) {

         edges.push_back((Edge){from, to, cap, , cost});

         edges.push_back((Edge){to, from, , , -cost});

         m = edges.size();

         G[from].push_back(m-);

         G[to].push_back(m-);

     }

     bool BellmanFord(int s, int t, int& flow, int& cost) {

         for (int i = ; i <= n; ++i) d[i] = inf;

         memset(inq, , sizeof(inq));

         d[s] = ; inq[s] = ; p[s] = ; a[s] = inf;

         queue<int> que;

         que.push(s);

         while (!que.empty()) {

             int u = que.front(); que.pop();

             inq[u] = ;

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

                 Edge& e = edges[G[u][i]];

                 if (e.cap > e.flow && d[e.to] > d[u] + e.cost) {

                     d[e.to] = d[u] + e.cost;

                     p[e.to] = G[u][i];

                     a[e.to] = min(a[u], e.cap-e.flow);

                     if (!inq[e.to]) { que.push(e.to); inq[e.to] = ; }

                 }

             }

         }

         if (d[t] == inf) return false;

         flow += a[t];

         cost += d[t] * a[t];

         int u = t;

         while (u != s) {

             edges[p[u]].flow += a[t];

             edges[p[u]^].flow -= a[t];

             u = edges[p[u]].from;

         }

         return true;

     }

     int mincost(int s, int t) {

         int flow = , cost = ;

         while (BellmanFord(s, t, flow, cost));

         return cost;

     }

 }mcmf;

 int a[maxn], b[maxn], c[maxn][maxn];

 int main() {

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

     int s = m+n+, t = m+n+;

     for (int i = ; i <= m; ++i) scanf("%d",&a[i]);

     for (int j = ; j <= n; ++j) scanf("%d",&b[j]);

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

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

             scanf("%d",&c[i][j]);

         }

     }

     // 最小费用最大流

     mcmf.init(n+m+);

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

         mcmf.AddEdge(s,i,a[i],);

     }

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

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

             mcmf.AddEdge(i,j+m,inf,c[i][j]);

         }

     }

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

         mcmf.AddEdge(j+m,t,b[j],);

     }

     printf("%d\n",mcmf.mincost(s,t));

     // 最大费用最大流

     mcmf.init(n+m+);

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

         mcmf.AddEdge(s,i,a[i],);

     }

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

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

             mcmf.AddEdge(i,j+m,inf,-c[i][j]);

         }

     }

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

         mcmf.AddEdge(j+m,t,b[j],);

     }

     printf("%d\n",-mcmf.mincost(s,t));

     return ;

 }