bzoj4016 [FJOI2014]最短路径树问题

#include<queue>
#include<cstdio>
#include<vector>
#include<cstring>
#include<algorithm>
using namespace std;
#define N 30050
#define M 60050
#define ll long long
inline int rd()
{
    int f=1,c=0;char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){c=10*c+ch-‘0‘;ch=getchar();}
    return f*c;
}
const int inf = 0x3f3f3f3f;
int n,m,K,hd[N],ct,hed[N],cnt;
struct EG
{
    int to,nxt,v;
}e1[2*M],e[2*N];
void ae1(int f,int t,int v)
{
    e1[++ct].to = t;
    e1[ct].nxt = hd[f];
    e1[ct].v = v;
    hd[f] = ct;
}
void ae(int f,int t,int v)
{
    e[++cnt].to = t;
    e[cnt].nxt = hed[f];
    e[cnt].v = v;
    hed[f] = cnt;
}
int dis[N];
bool vis[N];
struct Pair
{
    int x,d;
    Pair(){}
    Pair(int x,int d):x(x),d(d){}
    friend bool operator < (Pair a,Pair b)
    {
        return a.d > b.d;
    }
}tp;
void dij()
{
    memset(dis,0x3f,sizeof(dis));
    dis[1]=0;
    priority_queue<Pair>q;
    q.push(Pair(1,0));
    while(!q.empty())
    {
        tp = q.top();
        q.pop();
        int u = tp.x;
        if(vis[u])continue;
        vis[u]=1;
        for(int j=hd[u];j;j=e1[j].nxt)
        {
            int to = e1[j].to;
            if(dis[to]>dis[u]+e1[j].v)
            {
                dis[to] = dis[u]+e1[j].v;
                q.push(Pair(to,dis[to]));
            }
        }
    }
}
int fa[N];
void build(int u)
{
    vector<int>ve;
    for(int j=hd[u];j;j=e1[j].nxt)
    {
        int to = e1[j].to;
        if(!fa[to]&&dis[to]==dis[u]+e1[j].v)
        {
            fa[to] = u;
            ve.push_back(to);
            ae(u,to,e1[j].v);
            ae(to,u,e1[j].v);
        }
    }
    sort(ve.begin(),ve.end());
    for(int i=0;i<ve.size();i++)
        build(ve[i]);
}
int rt,sum,mrk[N],w[N],siz[N];
void get_rt(int u,int fa)
{
    siz[u] = 1;w[u] = 0;
    for(int j=hed[u];j;j=e[j].nxt)
    {
        int to = e[j].to;
        if(mrk[to]||to==fa)continue;
        get_rt(to,u);
        siz[u]+=siz[to];
        if(siz[to]>w[u])w[u] = siz[to];
    }
    w[u] = max(w[u],sum-siz[u]);
    if(w[u]<w[rt])rt=u;
}
int f[N],g[N],max_dep;
ll sf[N],sg[N],as1,as2;
void dfs(int u,int fa,int dep,ll ds)
{
    if(dep>=K)return ;
    if(dep==K-1)
    {
        if(as1<ds)
        {
            as1 = ds;
            as2 = 1;
        }else if(as1==ds)
        {
            as2++;
        }
        return ;
    }
    if(f[dep]<ds)f[dep]=ds,sf[dep]=1;
    else if(f[dep]==ds)sf[dep]++;
    max_dep = max(max_dep,dep);
    for(int j=hed[u];j;j=e[j].nxt)
    {
        int to = e[j].to;
        if(to==fa||mrk[to])continue;
        dfs(to,u,dep+1,ds+e[j].v);
    }
}
void work(int u)
{
    mrk[u] = 1;int mx = 0;
    for(int j=hed[u];j;j=e[j].nxt)
    {
        int to = e[j].to;
        if(mrk[to])continue;
        max_dep = 0;
        dfs(to,u,1,e[j].v);
        mx = max(mx,max_dep);
        for(int i=1;i<=max_dep;i++)
        {
            if(g[K-i-1]!=-1)
            {
                if(f[i]+g[K-i-1]>as1)
                {
                    as1 = f[i]+g[K-i-1];
                    as2 = sf[i]*sg[K-i-1];
                }else if(f[i]+g[K-i-1]==as1)
                {
                    as2 += sf[i]*sg[K-i-1];
                }
            }
        }
        for(int i=1;i<=max_dep;i++)
        {
            if(f[i]>g[i])
            {
                g[i]=f[i];
                sg[i] = sf[i];
            }else if(f[i]==g[i])
            {
                sg[i] += sf[i];
            }
            f[i] = sf[i] = 0;
        }
    }
    for(int i=1;i<=mx;i++)
        g[i]=-1,sg[i]=0;
    for(int j=hed[u];j;j=e[j].nxt)
    {
        int to = e[j].to;
        if(mrk[to])continue;
        rt = 0,sum = siz[to];
        get_rt(to,0);
        work(rt);
    }
}
int main()
{
    n = rd(),m = rd(),K = rd();
    for(int f,t,v,i=1;i<=m;i++)
    {
        f = rd(),t = rd(),v = rd();
        ae1(f,t,v),ae1(t,f,v);
    }
    dij();fa[1]=-1;
    build(1);
    w[0] = inf;as1=-inf;
    memset(g,-1,sizeof(g));
    rt=0,sum=n;
    get_rt(1,0);
    work(rt);
    printf("%lld %lld\n",as1,as2);
    return 0;
}