QC的博客搬来http://www.cnblogs.com/pony1993/archive/2012/07/28/2612883.html
模板题poj1273http://www.cnblogs.com/pony1993/archive/2012/07/28/2612883.html
代码
View Code
1 #include <iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include<algorithm> 5 #include<queue> 6 #define INF 0x3f3f3f 7 using namespace std; 8 int n,m,path[210],map[210][210],flow[210],st,en; 9 int bfs() 10 { 11 int i,j,k; 12 memset(path,-1,sizeof(path)); 13 path[st] = 0; 14 flow[st]= INF; 15 queue<int>q; 16 q.push(st); 17 while(!q.empty()) 18 { 19 int mt = q.front(); 20 q.pop(); 21 if(mt==en) 22 break; 23 for(i = 1; i <= m ; i++)//找到新节点 24 { 25 if(i!=st&&path[i]==-1&&map[mt][i]) 26 { 27 flow[i] = min(flow[mt],map[mt][i]);//路径上的最小残量 28 q.push(i); 29 path[i] = mt; 30 } 31 } 32 } 33 if(path[en]==-1) 34 return -1; 35 return flow[en]; 36 } 37 int karp() 38 { 39 int i,j,k,ml = 0,now,pre; 40 while((k=bfs())!=-1)//bfs找增广路径 41 { 42 ml+=k; 43 now = en; 44 while(now!=st) 45 { 46 pre = path[now];//path保留节点的前驱 更新正向边的实际容量 47 map[pre][now]-=k; 48 map[now][pre]+=k;//增加逆向边的容量 49 now = pre; 50 } 51 } 52 return ml; 53 } 54 int main() 55 { 56 int i,j,k,g,a,b,c; 57 while(cin>>n>>m) 58 { 59 memset(map,0,sizeof(map)); 60 for(i = 1; i <= n ;i++) 61 { 62 cin>>a>>b>>c; 63 map[a][b]+=c; 64 } 65 st = 1,en = m; 66 cout<<karp()<<endl; 67 } 68 return 0; 69 }
多源点最大流
pojhttp://poj.org/problem?id=1459
增加一个源点与核电站相连 一个终点与c相连 d看做平常的节点
View Code
1 #include <iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include<algorithm> 5 #include<queue> 6 #define INF 0x3f3f3f 7 using namespace std; 8 int path[110],map[110][110],flow[110],en,st,m; 9 int bfs() 10 { 11 int i,j,k; 12 memset(path,-1,sizeof(path)); 13 path[st] = 0; 14 flow[st] = INF; 15 queue<int>q; 16 q.push(st); 17 while(!q.empty()) 18 { 19 int mt = q.front(); 20 q.pop(); 21 if(mt==en) 22 break; 23 for(i = 0; i <= en ; i++) 24 { 25 if(i!=st&&path[i]==-1&&map[mt][i]) 26 { 27 path[i] = mt; 28 flow[i] = min(flow[mt],map[mt][i]); 29 q.push(i); 30 31 } 32 } 33 } 34 if(path[en]==-1) 35 return -1; 36 return flow[en]; 37 } 38 int karp() 39 { 40 int i,j,k,now,ml=0,pre; 41 while((k=bfs())!=-1) 42 { 43 ml+=k; 44 now = en; 45 while(now!=st) 46 { 47 pre = path[now]; 48 map[pre][now]-=k; 49 map[now][pre]+=k; 50 now = pre; 51 } 52 } 53 return ml; 54 } 55 int main() 56 { 57 int i,j,k,g,n,nc,np,u,v,w; 58 char str[20],c1,c2,c3; 59 while(cin>>n>>np>>nc>>m) 60 { 61 getchar(); 62 memset(map,0,sizeof(map)); 63 for(i = 1; i <= m ; i++) 64 { 65 cin>>c1>>u>>c2>>v>>c3>>w; 66 map[u][v] += w; 67 } 68 for(i = 1; i <= np ; i++) 69 { 70 cin>>c1>>u>>c2>>w; 71 map[n][u] += w; 72 } 73 for(i = 1; i <= nc ; i++) 74 { 75 cin>>c1>>u>>c2>>w; 76 map[u][n+1] += w; 77 } 78 st = n; 79 en = n+1; 80 cout<<karp()<<endl; 81 } 82 return 0; 83 }