BZOJ 1937 最小生成树

KM的复杂度是不是又是迷啊。。。

跑的好快

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxv 1750
#define maxe 100050
#define inf 2000000000
using namespace std;
int n,m,g[maxv],nume=1,x[maxv],y[maxv],w[maxv],p,q;
int dis[maxv],anc[maxv][11],fath_e[maxv];
int map[maxv][maxv],slack[maxv],linky[maxv],lx[maxv],ly[maxv];
bool flag[maxv],visx[maxv],visy[maxv];
struct edge
{
    int v,w,id,nxt;
}e[maxe];
void addedge(int u,int v,int w,int id)
{
    e[++nume].v=v;e[nume].w=w;
    e[nume].id=id;e[nume].nxt=g[u];g[u]=nume;
}
void dfs(int x)
{
    for (int i=g[x];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if (v!=anc[x][0])
        {
            anc[v][0]=x;dis[v]=dis[x]+1;fath_e[v]=e[i].id;
            dfs(v);
        }
    }
}
void get_table()
{
    for (int e=1;e<=10;e++)
        for (int i=1;i<=n;i++)
            anc[i][e]=anc[anc[i][e-1]][e-1];
}
int lca(int x,int y)
{
    if (dis[x]<dis[y]) swap(x,y);
    for (int e=10;e>=0;e--)
    {
        if ((dis[anc[x][e]]>=dis[y]) && (anc[x][e]))
            x=anc[x][e];
    }
    if (x==y) return x;
    for (int e=10;e>=0;e--)
    {
        if (anc[x][e]!=anc[y][e])
        {
            x=anc[x][e];
            y=anc[y][e];
        }
    }
    return anc[x][0];
}
void build(int x,int pos,int id,int val)
{
    while (x!=pos)
    {
        map[id][fath_e[x]]=max(w[fath_e[x]]-val,0);
        x=anc[x][0];
    }
}
bool hungary(int x)
{
    visx[x]=true;
    for (int i=1;i<=m;i++)
    {
        if (visy[i]) continue;
        int t=lx[x]+ly[i]-map[x][i];
        if (!t)
        {
            visy[i]=true;
            if ((linky[i]==-1) || (hungary(linky[i])))
            {
                linky[i]=x;
                return true;
            }
        }
        else slack[i]=min(slack[i],t);
    }
    return false;
}
int KM()
{
    for (int i=1;i<=m;i++) lx[i]=-inf,ly[i]=0,linky[i]=-1;
    for (int i=1;i<=m;i++)
        for (int j=1;j<=m;j++)
            lx[i]=max(lx[i],map[i][j]);
    for (int i=1;i<=m;i++)
    {
        for (int j=1;j<=m;j++) slack[j]=inf;
        for (;;)
        {
            memset(visx,false,sizeof(visx));
            memset(visy,false,sizeof(visy));
            if (hungary(i)) break;
            int mn=inf;
            for (int j=1;j<=m;j++) if (!visy[j]) mn=min(mn,slack[j]);
            for (int j=1;j<=m;j++)
            {
                if (visx[j]) lx[j]-=mn;
                if (visy[j]) ly[j]+=mn;
                else slack[j]-=mn;
            }
        }
    }
    int ret=0;
    for (int i=1;i<=m;i++)
    {
        if (linky[i]==-1) continue;
        ret+=map[linky[i]][i];
    }
    return ret;
}
int main()
{
    scanf("%d%d",&n,&m);
    for (int i=1;i<=m;i++)
    {
        scanf("%d%d%d",&x[i],&y[i],&w[i]);
        if (x[i]>y[i]) swap(x[i],y[i]);
    }
    for (int i=1;i<n;i++)
    {
        scanf("%d%d",&p,&q);if (p>q) swap(p,q);
        for (int j=1;j<=m;j++)
        {
            if ((x[j]==p) && (y[j]==q))
            {
                addedge(p,q,w[j],j);addedge(q,p,w[j],j);
                flag[j]=true;break;    
            }    
        }
    }
    dfs(1);get_table();
    for (int i=1;i<=m;i++)
    {
        if (flag[i]) continue;
        int t=lca(x[i],y[i]);
        build(x[i],t,i,w[i]);
        build(y[i],t,i,w[i]);
    }
    printf("%d
",KM());
    return 0;
}