Submission #848279

#	Time	Username	Problem	Language	Result	Execution time	Memory
848279		wakandaaa	Museum (CEOI17_museum)	C++17	100 / 100	266 ms	785488 KiB

museum

#include <bits/stdc++.h>
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define getbit(x, i) (((x) >> (i)) & 1)
#define bit(x) (1 << (x))
#define file ""
using namespace std;
 
mt19937_64 rd(chrono::steady_clock::now().time_since_epoch().count());
long long rand(long long l, long long r) {
    return l + rd() % (r - l + 1);
}
 
const int N = 1e4 + 5;
const int mod = 1e9 + 7; // 998244353;
const int inf = INT_MAX;
const long long llinf = LLONG_MAX;
const int lg = 25; // lg + 1
 
template<class X, class Y> bool minimize(X &a, Y b) {
    return a > b ? (a = b, true) : false;
}
template<class X, class Y> bool maximize(X &a, Y b) {
    return a < b ? (a = b, true) : false;
}
template<class X, class Y> bool add(X &a, Y b) {
    a += b;
    while (a >= mod) a -= mod;
    while (a < 0) a += mod;
    return true;
}
 
int n, k, x;
vector<pair<int, int> > adj[N];
int sz[N];
int f[N][N][2];
 
void dfs(int u, int p) {
	sz[u] = 1;
	f[u][1][0] = f[u][1][1] = 0;
 
	for (auto [v, c] : adj[u]) if (v != p) {
		dfs(v, u);
		for (int i = min(k, sz[u]); i >= 0; --i)
			for (int j = min(k, sz[v]); j >= 0; --j) if (i + j <= k) {
				minimize(f[u][i + j][0], f[u][i][0] + f[v][j][0] + c * 2);
				minimize(f[u][i + j][1], f[u][i][1] + f[v][j][0] + c * 2);
				minimize(f[u][i + j][1], f[u][i][0] + f[v][j][1] + c);
			}
		sz[u] += sz[v];
	}
}
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
 
    // freopen(file".inp", "r",stdin);
    // freopen(file".out", "w",stdout);
 
    cin >> n >> k >> x;
    for (int i = 1; i < n; ++i) {
    	int u, v, c;
    	cin >> u >> v >> c;
    	adj[u].emplace_back(v, c);
    	adj[v].emplace_back(u, c);
    }
 
    memset(f, 0x3f, sizeof f);
 
    dfs(x, 0);
 
    cout << f[x][k][1];
    
    return 0;
}

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