Dinic

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <map>
 5 #include <algorithm>
 6 #include <queue>
 7 using namespace std;
 8 
 9 const int N = 210;
10 const int M=1001000;
11 const int INF = 1001001010;
12 struct edge{
13     int u,v,cap,flow;
14     int next;
15 
16     //////
17 }e[M];
18 int head[N],num;
19 int cur[N],d[N];
20 bool vis[N];
21 int s,t;
22 void _add(int u,int v,int cap){
23     e[num].u = u;e[num].v = v;
24     e[num].cap = cap;e[num].flow = 0;
25     e[num].next = head[u];
26 
27     //////
28     head[u] = num++;
29 }
30 
31 void add(int u,int v,int cap){
32     _add(u,v,cap); _add(v,u,0);
33 }
34 
35 bool BFS(){
36     memset(vis,0,sizeof(vis));
37     queue<int> Q;
38     Q.push(s);
39     d[s] = 0;
40     vis[s]=1;
41     while(!Q.empty()){
42         int x = Q.front(); Q.pop();
43         for(int i = head[x]; i != -1;i = e[i].next){
44             if(!vis[e[i].v] && e[i].cap > e[i].flow ){
45                 vis[e[i].v] = 1;
46                 d[e[i].v] = d[x] + 1;
47                 Q.push(e[i].v);
48             }
49         }
50     }
51     return vis[t];
52 }
53 
54 int DFS(int x, int a){
55     if(x == t || a == 0) return a;
56     int flow=0,f;
57 
58     for(int &i = cur[x]; i != -1; i = e[i].next){
59         if(d[x] + 1 == d[e[i].v] && (f = DFS(e[i].v, min(a, e[i].cap - e[i].flow))) > 0){
60             e[i].flow += f;
61             e[i ^ 1].flow -= f;
62             flow += f;
63             a -= f;
64             if(a == 0)break;
65         }
66     }
67     return flow;
68 }
69 int Dinic(){
70     int flow = 0;
71     while(BFS()){
72         memcpy(cur,head,sizeof(head));
73         flow += DFS(s,INF);
74     }
75     return flow;
76 }
77 void init(int n){
78     memset(head,-1,sizeof(head));
79     num=0;
80 }