1 /* 2 网络流之最大流Dinic算法模版 3 */ 4 #include <cstring> 5 #include <cstdio> 6 #include <queue> 7 using namespace std; 8 const int maxn = 205; 9 const int inf = 0x3f3f3f3f; 10 struct 11 { 12 int c,f;//c为边的容量，f为边的容量 13 }edge[maxn][maxn]; 14 int dis[maxn]; 15 int v,e; 16 bool bfs()//利用bfs进行分层处理，当汇点无法分层时得到最大流 17 { 18 memset(dis,0,sizeof dis); 19 queue<int> q; 20 q.push(1); 21 dis[1] = 1; 22 while(!q.empty()) 23 { 24 int u = q.front(); q.pop(); 25 for(int i = 1; i <= v; ++i) 26 if(!dis[i] && edge[u][i].c > edge[u][i].f) 27 {dis[i] = dis[u] + 1;q.push(i);} 28 } 29 return dis[v] != 0; 30 } 31 int dfs(int u,int c)//增广 32 { 33 if(u == v) return c; 34 int temp = c; 35 for(int i = 1; i <= v && temp; ++i) 36 { 37 if(dis[i] != dis[u] + 1 || edge[u][i].c <= edge[u][i].f) continue; 38 int t = dfs(i,min(temp,edge[u][i].c - edge[u][i].f)); 39 edge[u][i].f += t; edge[i][u].f -= t; temp -= t; 40 } 41 return c - temp; 42 } 43 int dinic() 44 { 45 int ans = 0; 46 while(bfs()) 47 while(int t = dfs(1,inf)) 48 ans += t; 49 return ans; 50 } 51 int main() 52 { 53 while(~scanf("%d%d",&e,&v)) 54 { 55 memset(edge,0,sizeof edge); 56 while(e--) 57 { 58 int x,y,z; 59 scanf("%d%d%d",&x,&y,&z); 60 edge[x][y].c += z; 61 } 62 int ans = dinic(); 63 printf("%d ",ans); 64 } 65 return 0; 66 }