（hdu-4280）Island Transport~测试网络流模板速度~要加挂才能过啊

  1 #include<stdio.h>
  2 #include<string>
  3 #include<string.h>
  4 #include<vector>
  5 #include<queue>
  6 using namespace std;
  7 #pragma comment(linker, "/STACK:1024000000,1024000000")
  8 const int maxn = 1e5 + 10;
  9 const int INF = 999999999;
 10 struct node {
 11     int from, to, cap, flow;
 12 };
 13 struct Dinic {
 14     int n, m, s, t;
 15     vector<node>nodes;
 16     vector<int>g[maxn];
 17     int vis[maxn];
 18     int d[maxn];
 19     int cur[maxn];
 20     void clearall(int n) {
 21         for (int i = 0 ; i < n ; i++) g[i].clear();
 22         nodes.clear();
 23     }
 24     void clearflow() {
 25         int len = nodes.size();
 26         for (int i = 0 ; i < len ; i++) nodes[i].flow = 0;
 27     }
 28     void add(int from, int to, int cap) {
 29         nodes.push_back((node) {
 30             from, to, cap, 0
 31         });
 32         nodes.push_back((node) {
 33             to, from, cap, 0
 34         });
 35         m = nodes.size();
 36         g[from].push_back(m - 2);
 37         g[to].push_back(m - 1);
 38     }
 39     bool bfs() {
 40         memset(vis, 0, sizeof(vis));
 41         queue<int>q;
 42         q.push(s);
 43         d[s] = 0;
 44         vis[s] = 1;
 45         while(!q.empty()) {
 46             int x = q.front();
 47             q.pop();
 48             int len = g[x].size();
 49             for (int i = 0 ; i < len ; i++) {
 50                 node &e = nodes[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     int dfs(int x, int a) {
 61         if  (x == t || a == 0) return a;
 62         int flow = 0, f, len = g[x].size();
 63         for (int &i = cur[x] ; i < len ; i++) {
 64             node & e = nodes[g[x][i]];
 65             if (d[x] + 1 == d[e.to] && (f = dfs(e.to, min(a, e.cap - e.flow))) > 0 ) {
 66                 e.flow += f;
 67                 nodes[g[x][i] ^ 1].flow -= f;
 68                 flow += f;
 69                 a -= f;
 70                 if (a == 0) break;
 71             }
 72         }
 73         return flow;
 74     }
 75     int maxflow(int a, int b) {
 76         s = a;
 77         t = b;
 78         int flow = 0;
 79         while(bfs()) {
 80             memset(cur, 0, sizeof(cur));
 81             flow += dfs(s, INF);
 82         }
 83         return flow;
 84     }
 85     vector<int>mincut() {
 86         vector<int>ans;
 87         int len = nodes.size();
 88         for (int i = 0 ; i < len ; i++) {
 89             node & e = nodes[i];
 90             if ( vis[e.from] && !vis[e.to] && e.cap > 0 ) ans.push_back(i);
 91         }
 92         return ans;
 93     }
 94     void reduce() {
 95         int len = nodes.size();
 96         for (int i = 0 ; i < len ; i++) nodes[i].cap -= nodes[i].flow;
 97     }
 98 } f;
 99 int main() {
100     int n, m, t;
101     scanf("%d", &t);
102     while(t--) {
103         scanf("%d%d", &n, &m);
104         f.clearall(n);
105         f.clearflow();
106         int left = INF, right = -INF, s = 1, t = 1;
107         for (int i = 1 ; i <= n ; i++) {
108             int x, y;
109             scanf("%d%d", &x, &y);
110             if (x < left) {
111                 left = x;
112                 s = i;
113             }
114             if (x > right) {
115                 right = x;
116                 t = i;
117             }
118         }
119         for (int i = 0 ; i < m ; i++) {
120             int u, v, c;
121             scanf("%d%d%d", &u, &v, &c);
122             f.add(u, v, c);
123         }
124         printf("%d\n", f.maxflow(s, t));
125     }
126     return 0;
127 }