PKU

PKU/3308 - Paratroopers.cpp

@@ -0,0 +1,120 @@
+#include <cstdio>
+#include <climits>
+#include <cmath>
+#include <algorithm>
+
+using namespace std;
+
+struct flow_graph{
+    int MAX_V,E,s,t,head,tail;
+    int *to,*next,*last,*dist,*q,*now;
+    double *cap;
+
+    flow_graph(){}
+
+    flow_graph(int V, int MAX_E){
+        MAX_V = V; E = 0;
+        cap = new double[2*MAX_E], to = new int[2*MAX_E], next = new int[2*MAX_E];
+        last = new int[MAX_V], q = new int[MAX_V];
+        dist = new int[MAX_V], now = new int[MAX_V];
+        fill(last,last+MAX_V,-1);
+    }
+
+    void clear(){
+        fill(last,last+MAX_V,-1);
+        E = 0;
+    }
+
+    void add_edge(int u, int v, double uv, double vu = 0){
+        to[E] = v, cap[E] = uv, next[E] = last[u]; last[u] = E++;
+        to[E] = u, cap[E] = vu, next[E] = last[v]; last[v] = E++;
+    }
+
+    bool bfs(){
+        fill(dist,dist+MAX_V,-1);
+        head = tail = 0;
+
+        q[tail] = t; ++tail;
+        dist[t] = 0;
+
+        while(head<tail){
+            int v = q[head]; ++head;
+
+            for(int e = last[v];e!=-1;e = next[e]){
+                if(cap[e^1]>1e-7 && dist[to[e]]==-1){
+                    q[tail] = to[e]; ++tail;
+                    dist[to[e]] = dist[v]+1;
+                }
+            }
+        }
+
+        return dist[s]!=-1;
+    }
+
+    double dfs(int v, double f){
+        if(v==t) return f;
+
+        for(int &e = now[v];e!=-1;e = next[e]){
+            if(cap[e]>1e-7 && dist[to[e]]==dist[v]-1){
+                double ret = dfs(to[e],min(f,cap[e]));
+
+                if(ret>1e-7){
+                    cap[e] -= ret;
+                    cap[e^1] += ret;
+                    return ret;
+                }
+            }
+        }
+
+        return 0;
+    }
+
+    double max_flow(int source, int sink){
+        s = source; t = sink;
+        double f = 0,df;
+
+        while(bfs()){
+            for(int i = 0;i<MAX_V;++i) now[i] = last[i];
+
+            while(true){
+                df = dfs(s,10);
+                if(df<1e-7) break;
+                f += df;
+            }
+        }
+
+        return f;
+    }
+}G(102,600);
+
+int main(){
+    int T,R,C,N;
+    double x;
+
+    scanf("%d",&T);
+
+    while(T--){
+        scanf("%d %d %d",&R,&C,&N);
+        G.clear();
+
+        for(int i = 0;i<R;++i){
+            scanf("%lf",&x);
+            G.add_edge(0,1+i,log(x));
+        }
+
+        for(int i = 0;i<C;++i){
+            scanf("%lf",&x);
+            G.add_edge(1+R+i,1+R+C,log(x));
+        }
+
+        for(int i = 0,r,c;i<N;++i){
+            scanf("%d %d",&r,&c);
+            --r; --c;
+            G.add_edge(1+r,1+R+c,10);
+        }
+
+        printf("%.4f\n",exp(G.max_flow(0,1+R+C)));
+    }
+
+    return 0;
+}