Submission #1282918

#	Time	Username	Problem	Language	Result	Execution time	Memory
1282918		mlecio	경주 (Race) (IOI11_race)	C++20	100 / 100	333 ms	32280 KiB

race

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

int n, k;
vector<pair<int, int>> Ver[200005];
int naj[1000006];
bool kil[200005];
vector<int> czy;
int sz[200005];
int ans = 1e9 + 1;

int dfs_sz(int u, int v) {
    sz[u] = 1;
    for (auto &x : Ver[u]) {
        if (x.first != v && !kil[x.first]) {
            sz[u] += dfs_sz(x.first, u);
        }
    }
    return sz[u];
}

void upd(int u, bool cz, int suma, int ile, int v) {
    if (suma > k) return;
    czy.emplace_back(suma);
    if (cz) {
        ans = min(ans, naj[k - suma] + ile);
    } else {
        naj[suma] = min(naj[suma], ile);
    }
    for (auto &x : Ver[u]) {
        if (!kil[x.first] && x.first != v) {
            upd(x.first, cz, suma + x.second, ile + 1, u);
        }
    }
}

int cent(int u, int v, int nk) {
    for (auto &x : Ver[u]) {
        if (x.first != v && !kil[x.first] && 2 * sz[x.first] > nk)
            return cent(x.first, u, nk);
    }
    return u;
}

void centroid(int u) {
    int root = cent(u, -1, dfs_sz(u, -1));
    kil[root] = 1;
    czy.clear();

    for (auto &x : Ver[root]) {
        if (!kil[x.first]) {
            upd(x.first, 1, x.second, 1, root);
            upd(x.first, 0, x.second, 1, root);
        }
    }

    for (auto &x : czy) {
        naj[x] = 1e9 + 2137;
    }

    for (auto &x : Ver[root]) {
        if (!kil[x.first])
            centroid(x.first);
    }
}

int best_path(int N, int K, int V[][2], int len[]) {
    n = N;
    k = K;
    for (int i = 0; i < n - 1; i++) {
        Ver[V[i][0] + 1].push_back({V[i][1] + 1, len[i]});
        Ver[V[i][1] + 1].push_back({V[i][0] + 1, len[i]});
    }
    fill(naj, naj + 1000006, 1e9 + 2137);
    naj[0] = 0;
    centroid(1);
    return (ans == 1e9 + 1 ? -1 : ans);
}

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