Submission #788809

#	Time	Username	Problem	Language	Result	Execution time	Memory
788809		LeVanThuc	Museum (CEOI17_museum)	C++17	100 / 100	192 ms	140628 KiB

museum

#include<bits/stdc++.h>
using namespace std;
#define ll int
#define fi first
#define se second
#define p(x,y) pair<ll,ll>(x,y)
#define BIT(i,x) ((x>>i)&1)
#define MASK(x) (1<<x)
#define ld long double
#define __builtin_popcount __builtin_popcountll
#define pll pair<ll,ll>
template<class T1,class T2>
bool maximize(T1 &x,const T2 &y)
{
    if(x<y)
    {
        x=y;
        return 1;
    }
    return 0;
}
template<class T1,class T2>
bool minimize(T1 &x,const T2 &y)
{
    if(x>y)
    {
        x=y;
        return 1;
    }
    return 0;
}
void online()
{
    std::ios_base::sync_with_stdio(0);
    cin.tie(0);
#ifndef ONLINE_JUDGE
//    freopen("input.inp", "r", stdin);
//    freopen("output.out","w", stdout);
#else
#endif
}
const ll N=1e4+10,M=5e8+7;
vector<ll> f[N][2];
ll f1[2][N],tt,n,x,c[N],par[N],cost[N];
vector<pll> gr[N];
void dfs(ll u)
{
    ll h=0;
    c[u]=1;
    for(auto [v,w]:gr[u])
    {
        if(v==par[u]) continue;
        par[v]=u;
        cost[v]=w;
        dfs(v);
        c[u]+=c[v];
        if(c[v]>c[h]) h=v;
    }
    f[u][0].resize(min(c[u],tt)+2,M);
    f[u][1].resize(min(c[u],tt)+2,M);
    f[u][0][1]=f[u][1][1]=0;
    ll cr=1;
    if(h)
    {
        for(int i=1;i<=min(c[h],tt);i++)
        {
            minimize(f[u][0][i+1],f[h][0][i]+2*cost[h]);
            minimize(f[u][1][i+1],f[h][1][i]+cost[h]);
        }
        cr+=c[h];
    }
    for(auto [v,w]:gr[u])
    {
        if(v==h||v==par[u]) continue;
        cr+=c[v];
        minimize(cr,tt);
        for(int k=0;k<=cr;k++) f1[0][k]=f[u][0][k],f1[1][k]=f[u][1][k];
        for(int k=2;k<=cr;k++)
        {
            for(int j=1;j<=min(k-1,c[v]);j++)
            {
                minimize(f1[0][k],f[u][0][k-j]+f[v][0][j]+2*w);
                minimize(f1[1][k],f[u][1][k-j]+f[v][0][j]+2*w);
                minimize(f1[1][k],f[u][0][k-j]+f[v][1][j]+w);
            }
        }
        for(int k=0;k<=cr;k++) f[u][0][k]=f1[0][k],f[u][1][k]=f1[1][k];
    }
}
int main()
{
    online();
    cin>>n>>tt>>x;
    for(int i=1;i<n;i++)
    {
        ll u,v,w;
        cin>>u>>v>>w;
        gr[u].emplace_back(v,w);
        gr[v].emplace_back(u,w);
    }
    dfs(x);
    cout<<f[x][1][tt];
}

• Subtask 1: 20 / 20
• Subtask 2: 25 / 25
• Subtask 3: 35 / 35
• Subtask 4: 20 / 20