Submission #923863

#	Time	Username	Problem	Language	Result	Execution time	Memory
923863		Whisper	Race (IOI11_race)	C++17	100 / 100	276 ms	39688 KiB

race

#include "race.h"
#include <bits/stdc++.h>
 
using namespace std;
using ll = long long;
using ld = long double;
using T = tuple<ll, ll, ll>;
 
//#define int long long
#define Base 41
#define sz(a) (int)a.size()
#define FOR(i, a, b) for ( int i = a ; i <= b ; i++ )
#define FORD(i, a, b) for (int i = b; i >= a; i --)
#define REP(i, n) for (int i = 0; i < n; ++i)
#define REPD(i, n) for (int i = n - 1; i >= 0; --i)
#define all(x) x.begin() , x.end()
#define pii pair<int , int>
#define fi first
#define se second
#define Lg(x) 31 - __builtin_clz(x)
 
#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)
 
constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int MAX = 2e5 + 5;
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
 
template <class X, class Y>
    bool minimize(X &x, const Y &y){
        X eps = 1e-9;
        if (x > y + eps) {x = y; return 1;}
        return 0;
    }
 
template <class X, class Y>
    bool maximize(X &x, const Y &y){
        X eps = 1e-9;
        if (x + eps < y) {x = y; return 1;}
        return 0;
    }
int numNode, k;
vector<pii> adj[MAX];
 
int sz[MAX], del[MAX];
void reSubsize(int u, int p){
    sz[u] = 1;
    for (auto&[v, w] : adj[u]) if(v ^ p){
        if (del[v]) continue;
        reSubsize(v, u);
        sz[u] += sz[v];
    }
}
int getCentroid(int u, int p, int siz){
    for (auto&[v, w] : adj[u]) if(v ^ p){
        if (!del[v] && sz[v] * 2 > siz) return getCentroid(v, u, siz);
    }
    return u;
}
ll f[5 * MAX];
ll ans = LINF;
vector<int> save;
void dfs(int u, int p, int l, int dep, bool ok){
    if (l > k) return;
    if (ok) minimize(ans, f[k - l] + dep);
    else{
        minimize(f[l], dep);
        save.push_back(l);
    }
    for (auto&[v, w] : adj[u]) if(v ^ p){
        if (!del[v]) dfs(v, u, l + w, dep + 1, ok);
    }
}
void decompose(int root){
    reSubsize(root, -1);
    int siz = sz[root];
    root = getCentroid(root, -1, siz);
    del[root] = 1;
  	f[0] = 0;
    for (auto&[v, w] : adj[root]){
        if (del[v]) continue;
        dfs(v, root, w, 1, 1);
        dfs(v, root, w, 1, 0);
    }
    for (auto&v : save) f[v] = 1e18;
    save.clear();
    for (auto&[v, w] : adj[root]) if (!del[v]){
        decompose(v);
    }
}
 
int best_path(int N, int K, int H[][2], int L[]) {
    numNode = N, k = K;
    for (int i = 0; i < numNode - 1; ++i){
        int u = H[i][0], v = H[i][1], w = L[i];
        ++u, ++v;
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }
    memset(f, 0x3f, sizeof f);
    decompose(1);
    return (ans > 1e15 ? -1 : ans);
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 22 / 22
• Subtask 4: 57 / 57