HDU6214 Smallest Minimum Cut

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #include <vector>
 5 #include <queue>
 6 using namespace std;
 7 #define next Next
 8 const int inf = 0x3f3f3f3f;
 9 const int maxn=205;
10 int level[maxn];
11 int iter[maxn];
12 int head[maxn],tot;
13 struct edge{
14     int to,cap,Next;
15 } e[2005]; ///此处应为边的两倍，加一条容量为0的反向边
16 void init(){
17     memset(head,-1,sizeof(head));
18     tot=0;
19 }
20 void add(int from,int to,int cap){
21     e[tot].Next=head[from];
22     e[tot].to=to;
23     e[tot].cap=cap;
24     head[from]=tot;
25     tot++;
26 }
27 void addedge(int from,int to,int cap){
28     add(from,to,cap);
29     add(to,from,0);
30 }
31 void bfs(int s){
32     memset(level,-1,sizeof(level));
33     queue<int> q;
34     level[s]=0;
35     q.push(s);
36     while(!q.empty()){
37         int v=q.front(); q.pop();
38         for(int i=head[v];~i;i=e[i].Next){
39             edge &ed=e[i];
40             if(ed.cap>0&&level[ed.to]<0){
41                 level[ed.to]=level[v]+1;
42                 q.push(ed.to);
43             }
44         }
45     }
46 }
47 int dfs(int v,int t,int f){
48     if(v==t) return f;
49     for(int &i=iter[v];~i;i=e[i].Next){
50         edge &ed=e[i];
51         if(ed.cap>0&&level[v]<level[ed.to]){
52             int d=dfs(ed.to,t,min(f,ed.cap));
53             if(d>0){
54                 ed.cap-=d;
55                 e[i^1].cap+=d;
56                 return d;
57             }
58         }
59     }
60     return 0;
61 }
62 int max_flow(int s,int t){
63     int flow=0;
64     while(1){
65         bfs(s);
66         if(level[t]<0) return flow;
67         memcpy(iter,head,sizeof(iter));
68         int f;
69         while((f=dfs(s,t,inf))>0){
70             flow+=f;
71         }
72     }
73 }
74 int main()
75 {
76     int n,m,T;
77     scanf("%d",&T);
78     while(T--)
79     {
80         init();
81         int s,t;
82         scanf("%d %d",&n,&m);
83         scanf("%d %d",&s,&t);
84         for(int i=1;i<=m;i++)
85         {
86             int u,v,w;
87             scanf("%d %d %d",&u,&v,&w);
88             addedge(u,v,w*300+1);
89         }
90         int ans = max_flow(s,t);
91         printf("%d\n",ans%300);
92     }
93     return 0;
94 }