Submission #1200279

#	Time	Username	Problem	Language	Result	Execution time	Memory
1200279		timasdfadsfadsf	Race (IOI11_race)	C++20	100 / 100	982 ms	65108 KiB

race

// time-limit: 3000
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;

using namespace std;

void setIO(string File_name) {
    cin.tie(0)->sync_with_stdio(0);
    if (File_name.size()) {
        freopen((File_name + ".in").c_str(), "r", stdin);
        freopen((File_name + ".out").c_str(), "w", stdout);
    }
}

class CD {
private:
    vector<vector<pair<int, int>>> tree;
    vector<int> sub;
    vector<bool> rem;
    gp_hash_table<int, pair<int, int>> mp;
    int ans = -1;
    int k;
    int dfs(int u, int p) {
        sub[u] = 1;
        for (auto [v, w] : tree[u]) {
            if (!rem[v] && v != p) {
                sub[u] += dfs(v, u);
            }
        }
        return sub[u];
    }
    int dfs(int u, int p, int n) {
        for (auto [v, w] : tree[u]) {
            if (!rem[v] && v != p && sub[v] > n / 2) {
                return dfs(v, u, n);
            }
        }
        return u;
    }

    void process(int u, int p, int depth, long long sum, bool filling, int c) {
        int need = k - sum;
        if (need < 0) return;
        if (filling) {
            if (mp.find(sum) == mp.end() || mp[sum].second != c) {
                mp[sum] = {depth, c};
            }
            else {
                mp[sum].first = min(mp[sum].first, depth);
            }
        }
        else if (mp.find(need) != mp.end() && mp[need].second == c) {
            if (ans == -1) {
                ans = depth + mp[need].first;
            }
            else if (depth + mp[need].first < ans) {
                ans = depth + mp[need].first;
            }
        }
        for (auto [v, w] : tree[u]) {
            if (v != p && !rem[v]) {
                process(v, u, depth + 1, sum + w, filling, c);
            }
        }
    }

    void build(int u, int p) {
        int n = dfs(u, p);
        int c = dfs(u, p, n);
        rem[c] = true;
        mp[0] = {0, c};
        for (auto [v, w] : tree[c]) {
            if (!rem[v]) {
                process(v, c, 1, w, 0, c);
                process(v, c, 1, w, 1, c);
            }
        }
        for (auto [v, w] : tree[c]) {
            if (!rem[v]) {
                build(v, u);
            }
        }
    }
public:
    CD(const vector<vector<pair<int, int>>>& t, int k_) {
        int n = t.size();
        sub.resize(n);
        rem.resize(n);
        tree = t;
        k = k_;
        build(0, -1);
    }
    int solve() {
        return ans;
    }
};

struct edge {
    int u, v, w;
};

int best_path(int n, int k, int h[][2], int* l) {
    vector<edge> E(n - 1);
    for (int i = 0; i < n - 1; i++) {
        int u = h[i][0], v = h[i][1];
        E[i] = {u, v, -1};
    }
    for (int i = 0; i < n - 1; i++) {
        int ll = l[i];
        E[i].w = ll;
    }
    vector<vector<pair<int, int>>> t(n);
    for (auto e : E) {
        t[e.u].push_back({e.v, e.w});
        t[e.v].push_back({e.u, e.w});
    }
    CD g(t, k);
    return g.solve();
}

Compilation message (stderr)

race.cpp: In function 'void setIO(std::string)':
race.cpp:11:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 |         freopen((File_name + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
race.cpp:12:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   12 |         freopen((File_name + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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