BZOJ 4519 不同的最小割

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
#define maxe 200050
#define maxv 1050
const int inf=0x7fffffff/2;
using namespace std;
struct edge
{
int v,f,nxt;
}e[maxe];
int n,m,a,b,c,g[maxv],fath[maxv],f[maxv][maxv];
int map[maxv][maxv],nume,s,t;
int dis[maxv],regis[800500];
bool vis[maxv];
queue <int> q;
void addedge(int u,int v,int f)
{
e[++nume].v=v;
e[nume].f=f;
e[nume].nxt=g[u];
g[u]=nume;
e[++nume].v=u;
e[nume].f=0;
e[nume].nxt=g[v];
g[v]=nume;
}
void build()
{
nume=1;memset(g,0,sizeof(g));
for (int i=1;i<=n;i++)
for (int j=1;j<=n;j++)
{
if (map[i][j])    addedge(i,j,map[i][j]);
}
}
bool bfs()
{
while (!q.empty()) q.pop();
memset(dis,0,sizeof(dis));
memset(vis,false,sizeof(vis));
q.push(s);dis[s]=0;vis[s]=true;
while (!q.empty())
{
int head=q.front();
q.pop();
for (int i=g[head];i;i=e[i].nxt)
{
int v=e[i].v;
if ((e[i].f>0) && (!vis[v]))
{
vis[v]=true;
dis[v]=dis[head]+1;
q.push(v);
}
}
}
return dis[t]>0;
}
int dinic(int x,int low)
{
if (x==t) return low;
else
{
int ret=0;
for (int i=g[x];low && i;i=e[i].nxt)
{
int v=e[i].v;
if ((e[i].f>0) && (dis[v]==dis[x]+1))
{
int dd=dinic(v,min(low,e[i].f));
ret+=dd;low-=dd;
e[i].f-=dd;e[i^1].f+=dd;
}
}
if (!ret) dis[x]=0;
return ret;
}
}
int max_flow(int x,int y)
{
s=x;t=y;
int now=0;
while (bfs())
now+=dinic(s,inf);
return now;
}
void dfs(int now)
{
vis[now]=true;
for (int i=g[now];i;i=e[i].nxt)
{
int v=e[i].v;
if ((e[i].f>0) && (!vis[v])) dfs(v);
}
}
void Gusfield()
{
for (int i=1;i<=n;i++) fath[i]=1;
for (int i=1;i<=n;i++)
for (int j=1;j<=n;j++)
f[i][j]=inf;
for (int i=2;i<=n;i++)
{
build();
int maxf=max_flow(fath[i],i);
memset(vis,false,sizeof(vis));
dfs(fath[i]);
for (int j=1;j<i;j++)
f[i][j]=f[j][i]=min(f[j][fath[i]],maxf);
for (int j=i+1;j<=n;j++)
{
if ((fath[i]==fath[j]) && (!vis[j]))
fath[j]=i;
}
}
}
void get_ans()
{
int cnt=0;
for (int i=1;i<=n;i++)
{
for (int j=1;j<=n;j++)
{
if (f[i][j]!=inf)
regis[++cnt]=f[i][j];
}
}
sort(regis+1,regis+cnt+1);
int ans=unique(regis+1,regis+cnt+1)-regis-1;
printf("%d\n",ans);
}
int main()
{
scanf("%d%d",&n,&m);
for (int i=1;i<=m;i++)
{
scanf("%d%d%d",&a,&b,&c);
map[a][b]+=c;map[b][a]+=c;
}
Gusfield();
get_ans();
return 0;
}