Submission #923858

#	Time	Username	Problem	Language	Result	Execution time	Memory
923858		atom	Race (IOI11_race)	C++17	31 / 100	196 ms	38772 KiB

race

#include "bits/stdc++.h"
// @JASPER'S BOILERPLATE
using namespace std;
using ll = long long;
using ull = unsigned long long;
#define FOR(i, a, b) for(int i = a; i <= b; i++)
#define FORD(i, a, b) for(int i = a; i >= b; i--)
#define REP(i, b) for(int i = 0; i < b; i++)
#define PER(i, b) for(int i = b - 1; i >= 0; i--)
#define fi first
#define se second
#define all(x) x.begin(),x.end()
#ifdef JASPER2
#include "debug.h"
#else
#define debug(...) 166
#endif
 
using pii = pair < int, int >;
const ll LINF = 1e18 + 5;
const int INF = 1e9;
const int MOD = 1e9 + 7;
const int MAX = 2e5 + 5;
 
int n, k;
vector <pii> adj[MAX];
 
int cnt[MAX * 5];
int sz[MAX];
bool vis[MAX];
int Tsize = 0;
 
void reSubsize(int u, int p) {
    sz[u] = 1;
    for (auto &[w, v] : adj[u]) {
        if (v != p && !vis[v]) {
            reSubsize(v, u);
            sz[u] += sz[v];
        }
    }
}
 
int getCentroid(int u, int p) {
    for (auto &[w, v] : adj[u])
        if (v != p && !vis[v] && sz[v] > Tsize / 2)
            return getCentroid(v, u);
    return u;
}
 
int f[MAX * 5];
// f(i) : Minimum edge to form i length from subtree to current centroid (0 in sub;
int maxW, ans;
void process(int u, int p, int eCnt, int W) {
    if (W > k)
        return;
    ans = min(ans, eCnt + f[k - W]);
    maxW = max(maxW, W);
    for (auto &[w, v] : adj[u]) {
        if (v != p && !vis[v]) {
            process(v, u, eCnt + 1, W + w);
        }
    }
    f[W] = min(f[W], eCnt);
}
 
void decompose(int u, int p) {
    reSubsize(u, 0);
    Tsize = sz[u];
    int x = getCentroid(u, 0);
//    cnt[0] = 1;
    f[0] = 0;
    vis[x] = 1;
    maxW = 0;
 
//    debug(u, Tsize, x);
    vector <pii> valid;
    for (auto [w, v] : adj[x]) {
        if (!vis[v]) {
            process(v, x, 1, w);
            valid.push_back({w, v});
//            debug(v);
//            FOR(i, 1, n) {
//                debug(f[i]);
//            }
        }
    }
 
    for (int i = 0; i <= maxW; ++i) f[i] = INF;
    for (auto [w, v] : valid) {
        decompose(v, x);
    }
 
}
int N, K;
int H[MAX][2];
int L[MAX];
 
int best_path(int N, int K, int a[][2], int W[]) {
    cin >> n >> k;
    n = N, k = K;
    for (int i = 0; i < n; ++i) {
        int u = a[i][0], v = a[i][1], w = W[i];
        ++u, ++v;
        adj[u].push_back({w, v});
        adj[v].push_back({w, u});
    }
    ans = INF;
    for (int i = 0; i < MAX * 5; ++i) f[i] = INF;
    decompose(1, 0);
    if (ans == INF) ans = -1;
    return ans;
}

• Subtask 1: 9 / 9
• Subtask 2: 0 / 12
• Subtask 3: 22 / 22
• Subtask 4: 0 / 57