1 /* 2 网络流的最大流问题 3 刚学习Dinic算法。模版题 4 */ 5 #include <cstring> 6 #include <cstdio> 7 #include <queue> 8 using namespace std; 9 const int maxn = 205; 10 const int inf = 0x3f3f3f3f; 11 struct 12 { 13 int c,f; 14 }edge[maxn][maxn]; 15 int dis[maxn]; 16 int v,e; 17 bool bfs() 18 { 19 memset(dis,0,sizeof dis); 20 queue<int> q; 21 q.push(1); 22 dis[1] = 1; 23 while(!q.empty()) 24 { 25 int u = q.front(); q.pop(); 26 for(int i = 1; i <= v; ++i) 27 if(!dis[i] && edge[u][i].c > edge[u][i].f) 28 {dis[i] = dis[u] + 1;q.push(i);} 29 } 30 return dis[v] != 0; 31 } 32 int dfs(int u,int c) 33 { 34 if(u == v) return c; 35 int temp = c; 36 for(int i = 1; i <= v && temp; ++i) 37 { 38 if(dis[i] != dis[u] + 1 || edge[u][i].c <= edge[u][i].f) continue; 39 int t = dfs(i,min(temp,edge[u][i].c - edge[u][i].f)); 40 edge[u][i].f += t; edge[i][u].f -= t; temp -= t; 41 } 42 return c - temp; 43 } 44 int dinic() 45 { 46 int ans = 0; 47 while(bfs()) 48 while(int t = dfs(1,inf)) 49 ans += t; 50 return ans; 51 } 52 int main() 53 { 54 while(~scanf("%d%d",&e,&v)) 55 { 56 memset(edge,0,sizeof edge); 57 while(e--) 58 { 59 int x,y,z; 60 scanf("%d%d%d",&x,&y,&z); 61 edge[x][y].c += z; 62 } 63 int ans = dinic(); 64 printf("%d ",ans); 65 } 66 return 0; 67 }