BZOJ 4390 Max Flow

同运输计划。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxv 50050
#define maxe 100500
using namespace std;
struct edge
{
    int v,nxt;
}e[maxe];
int n,k,x,y,val[maxv],anc[maxv][],ans=,dis[maxv],g[maxv],nume=;
void addedge(int u,int v)
{
    e[++nume].v=v;
    e[nume].nxt=g[u];
    g[u]=nume;
}
void dfs1(int x)
{
    for (int i=g[x];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if (v!=anc[x][])
        {
            anc[v][]=x;dis[v]=dis[x]+;
            dfs1(v);
        }
    }
}
void get_table()
{
    for (int e=;e<=;e++)
        for (int i=;i<=n;i++)
            anc[i][e]=anc[anc[i][e-]][e-];
}
int lca(int x,int y)
{
     if (dis[x]<dis[y]) swap(x,y);
     for (int e=;e>=;e--)
     {
         if ((dis[anc[x][e]]>=dis[y]) && (anc[x][e]))
            x=anc[x][e];
     }
     if (x==y) return x;
     for (int e=;e>=;e--)
     {
         if (anc[x][e]!=anc[y][e])
         {
             x=anc[x][e];
             y=anc[y][e];
         }
     }
     return anc[x][];
}
void dfs2(int x)
{
    for (int i=g[x];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if (v!=anc[x][])
        {
           dfs2(v);
           val[x]+=val[v];
        }
    }
    ans=max(ans,val[x]);
}
int main()
{
     scanf("%d%d",&n,&k);
    for (int i=;i<=n-;i++)
    {
        scanf("%d%d",&x,&y);
        addedge(x,y);addedge(y,x);
    }
    dfs1();get_table();
    for (int i=;i<=k;i++)
    {
        scanf("%d%d",&x,&y);
        int t=lca(x,y);
        val[x]++;val[y]++;val[t]--;val[anc[t][]]--;
    }
    dfs2();
    printf("%d\n",ans);
    return ;
}