Submission #922927

#	Time	Username	Problem	Language	Result	Execution time	Memory
922927		a_l_i_r_e_z_a	Museum (CEOI17_museum)	C++17	100 / 100	302 ms	171344 KiB

museum

// In the name of God
// Hope is last to die

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define pb push_back
// #define int long long
#define S second
#define F first
#define mp make_pair
#define smax(x, y) (x) = max((x), (y))
#define smin(x, y) (x) = min((x), (y))
#define all(x) (x).begin(), (x).end()
#define len(x) ((int)(x).size())

const int maxn = 10000 + 5;
const int inf = 1e9 + 7;
int n, k, r, dp[maxn][maxn][2], tmp[maxn][2], cnt[maxn];
vector<pii> adj[maxn];

void dfs(int v, int p){
    cnt[v] = 1;
    for(auto [u, w]: adj[v]){
        if(u == p) continue;
        dfs(u, v);
        for(int i = 0; i <= cnt[v] + cnt[u]; i++) tmp[i][0] = tmp[i][1] = inf;
        for(int i = 1; i <= cnt[v]; i++){
            for(int j = 0; j <= cnt[u]; j++){
                if(j == 0){
                    smin(tmp[i][1], dp[v][i][1]);
                    smin(tmp[i][0], dp[v][i][0]);
                }
                else{
                    smin(tmp[i + j][1], dp[v][i][1] + dp[u][j][1] + 2 * w);
                    int x = min(dp[v][i][1] + w + dp[u][j][0], dp[v][i][0] + 2 * w + dp[u][j][1]);
                    smin(tmp[i + j][0], x);
                }
            }
        }
        cnt[v] += cnt[u];
        for(int i = 1; i <= cnt[v]; i++){
            dp[v][i][0] = tmp[i][0];
            dp[v][i][1] = tmp[i][1];
            smin(dp[v][i][0], dp[v][i][1]);
        }
    }
}

int32_t main()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    
    cin >> n >> k >> r;
    for(int i = 0; i < n - 1; i++){
        int u, v, w; cin >> u >> v >> w;
        adj[u].pb(mp(v, w));
        adj[v].pb(mp(u, w));
    }
    dfs(r, -1);
    cout << dp[r][k][0] << '\n';

    return 0;
}

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