HDU 1532

  1 #include <bits/stdc++.h>
  2 
  3 using namespace std;
  4 
  5 const int maxn = 205;
  6 const int INF = 0x3f3f3f3f;
  7 
  8 struct Edge {
  9     int from,to,cap,flow;
 10 };
 11 
 12 struct Dinic {
 13 
 14     int n,m,s,t;
 15     vector<Edge> edges;
 16     vector<int> G[maxn];
 17     bool vis[maxn];
 18     int d[maxn];
 19     int cur[maxn];
 20 
 21     void init(int n) {
 22         this->n = n;
 23         for(int i=0;i<n;i++)
 24             G[i].clear();
 25         edges.clear();
 26     }
 27 
 28     void clearflow() {
 29         for(int i=0;i<edges.size();i++)
 30             edges[i].flow = 0;
 31     }
 32 
 33 
 34     void AddEdge(int from,int to,int cap) {
 35         edges.push_back((Edge){from,to,cap,0});
 36         edges.push_back((Edge){to,from,0,0});
 37         m = edges.size();
 38         G[from].push_back(m-2);
 39         G[to].push_back(m-1);
 40     }
 41 
 42     bool BFS() {
 43         memset(vis,0,sizeof(vis));
 44         queue<int> Q;
 45         Q.push(s);
 46         vis[s] = 1;
 47         while(!Q.empty()) {
 48             int x = Q.front();Q.pop();
 49             for(int i=0;i<G[x].size();i++) {
 50                 Edge& e = edges[G[x][i]];
 51                 if(!vis[e.to]&&e.cap>e.flow) {
 52                     vis[e.to] = 1;
 53                     d[e.to] = d[x] + 1;
 54                     Q.push(e.to);
 55                 }
 56             }
 57         }
 58         return vis[t];
 59     }
 60 
 61 
 62     int DFS(int x,int a) {
 63         if(x==t||a==0) return a;
 64         int flow = 0,f;
 65         for(int& i=cur[x];i<G[x].size();i++) {
 66             Edge& e = edges[G[x][i]];
 67             if(d[x]+1==d[e.to]&&(f=DFS(e.to,min(a,e.cap-e.flow)))>0) {
 68                 e.flow +=f;
 69                 edges[G[x][i]^1].flow -=f;
 70                 flow+=f;
 71                 a-=f;
 72                 if(a==0) break;
 73             }
 74         }
 75         return flow;
 76     }
 77 
 78     int Maxflow(int s,int t) {
 79         this->s = s;this->t = t;
 80         int flow = 0;
 81         while(BFS()) {
 82             memset(cur,0,sizeof(cur));
 83             flow+=DFS(s,INF);
 84         }
 85         return flow;
 86     }
 87 
 88 
 89 }sol;
 90 
 91 int main()
 92 {
 93     int n,m;
 94     while(~scanf("%d%d",&n,&m)) {
 95         sol.init(n);
 96         for(int i=0;i<n;i++) {
 97             int u,v,c;
 98             scanf("%d%d%d",&u,&v,&c);
 99             u--;
100             v--;
101             sol.AddEdge(u,v,c);
102         }
103 
104        // int ans = -1;
105        // for(int s=0;s<m;s++) {
106        //     for(int t=s+1;t<m;t++) {
107        //         sol.clearflow();
108        //         ans = max(ans,sol.Maxflow(s,t));
109        //     }
110        // }
111 
112        // int ans = sol.Maxflow(0,m-1);
113 
114       // int s = m,t=m+1;
115        //for(int i=0;i<m;i++) {
116        //     sol.AddEdge(s,i,INF);
117       //      sol.AddEdge(i,t,INF);
118        //}
119 
120        printf("%d\n",sol.Maxflow(0,m-1));
121 
122        // printf("%d\n",ans);
123 
124     }
125     return 0;
126 }