luogu3329 [ZJOI2011]最小割 （最小割树）

直接暴力统计就行

但是如果碰到数据范围比较大的统计答案，
或者直接就是一个类似

查询树上两点间 $min$小于等于某个数的点对个数

可以直接将所有边按照权值从大到小排序，然后每次合并，如果这个边的权值是合法，那么就将 $siz$乘起来，加入答案。

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<queue>
#include<map>
#include<set>
#define mk make_pair
#define ll long long

using namespace std;

inline int read()
{
  int x=0,f=1;char ch=getchar();
  while (!isdigit(ch)) {if (ch=='-') f=-1;ch=getchar();}
  while (isdigit(ch)) {x=(x<<1)+(x<<3)+ch-'0';ch=getchar();}
  return x*f;
}

const int maxn = 410;
const int maxm = 2e5+1e5;
const int inf = 1e9;

int cnt=1,n,m;
int point[maxn],nxt[maxm],to[maxm],val[maxm];
int h[maxn];
int s,t;

void addedge(int x,int y,int w)
{
	nxt[++cnt]=point[x];
	to[cnt]=y;
	val[cnt]=w;
	point[x]=cnt; 
}

void insert(int x,int y,int w)
{
	addedge(x,y,w);
	addedge(y,x,0);
}

queue<int> q;

bool bfs(int s)
{
	memset(h,-1,sizeof(h));
	h[s]=0;
	q.push(s);
	while (!q.empty())
	{
		int x = q.front();
		q.pop();
		for (int i=point[x];i;i=nxt[i])
		{
			int p = to[i];
			if (h[p]==-1 && val[i]>0)
			{
				h[p]=h[x]+1;
				q.push(p);
			}
		}
	}
	if (h[t]==-1) return false;
	return true;
}

int dfs(int x,int low)
{
	if (x==t || low==0) return low;
	int totflow=0;
	for (int i=point[x];i;i=nxt[i])
	{
		int p = to[i];
		if (h[p]==h[x]+1 && val[i]>0)
		{
			int tmp = dfs(p,min(low,val[i]));
			val[i]-=tmp;
			val[i^1]+=tmp;
			low-=tmp;
			totflow+=tmp;
			if (low==0) return totflow; 
		}
	}
	if (low>0) h[x]=-1;
	return totflow;
}

int a[maxn],b[maxn],c[maxn];
int tot;
int x[maxm],y[maxm],w[maxm];
int ans[maxn][maxn];

void init()
{
	cnt=1;
	memset(point,0,sizeof(point));
}

int dinic(int ss,int tt)
{
	init();
	int ans=0;
	s=ss;
	t=tt;
	for (int i=1;i<=m;i++) insert(x[i],y[i],w[i]),insert(y[i],x[i],w[i]);
	while(bfs(s)) ans=ans+dfs(s,inf);
	return ans;
}

int col[maxn];

struct tree{
	int point[maxn],nxt[maxm],to[maxm];
	int cnt,val[maxm];
	void init()
	{
		cnt=0;
		memset(point,0,sizeof(point));
	}
	void addedge(int x,int y,int w)
	{
		nxt[++cnt]=point[x];
		to[cnt]=y;
		val[cnt]=w;
		point[x]=cnt;
	}
	void dfs(int x,int st,int fa,int mn)
	{
		if (fa!=0) ans[st][x]=ans[x][st]=mn;
		for (int i=point[x];i;i=nxt[i])
		{
			int p = to[i];
			if (p==fa) continue;
			dfs(p,st,x,min(mn,val[i]));
		}
	}
};

tree f;

void find(int x,int wei)
{
   col[x]=wei;
   for (int i=point[x];i;i=nxt[i])
   {
   	 int p = to[i];
   	 if (col[p]!=wei && val[i]>0)
   	   find(p,wei);
   }	
}

void build(int l,int r)
{
    if (l>=r) return;
    int x = a[l],y=a[l+1];
    int now = dinic(x,y);
    f.addedge(x,y,now);
    f.addedge(y,x,now);
    ++tot;
    find(x,tot);//cout<<l<<" "<<r<<endl; 
    int num=l-1,num1=0,num2=0;
    for (int i=l;i<=r;i++) if (col[a[i]]==tot) b[++num1]=a[i];
    else c[++num2]=a[i];
    for (int i=1;i<=num1;i++) a[++num]=b[i];
    for (int i=1;i<=num2;i++) a[++num]=c[i];
    build(l,l+num1-1);
    build(l+num1,r);
}

int T;

int main()
{
  cin>>T;
  while (T--)
  {
  	  f.init();
  	  init();
  	  n=read(),m=read();
  	  for (int i=1;i<=m;i++) x[i]=read(),y[i]=read(),w[i]=read();
  	  for (int i=1;i<=n;i++) a[i]=i;
  	  build(1,n);
  	  //cout<<1<<endl;
  	  for (int i=1;i<=n;i++) f.dfs(i,i,0,1e9);
  	  int q=read();
  	  for (int i=1;i<=q;i++)
  	  {
  	  	  int x=read();
  	  	  int tmp=0;
  	  	  for (int j=1;j<=n;j++)
  	  	    for (int k=j+1;k<=n;k++)
  	  	      if (ans[j][k]<=x) ++tmp;
  	  	  cout<<tmp<<"\n";
	  }
	  cout<<"\n";
  }
  return 0;
}