Submission #1311858

#	Time	Username	Problem	Language	Result	Execution time	Memory
1311858		nikaa123	Simurgh (IOI17_simurgh)	C++20	0 / 100	1 ms	340 KiB

simurgh

#include "simurgh.h"
#include <bits/stdc++.h>

using namespace std;

static int status[300005]; 
static vector<pair<int, int>> adj[505];
static int depth[505], parent_n[505], parent_e[505];
static bool vis[505];
static vector<int> tree_edges;
static bool is_te[300005];

struct DSU {
    vector<int> p;
    DSU(int n) { p.resize(n); iota(p.begin(), p.end(), 0); }
    int find(int i) { return (p[i] == i) ? i : (p[i] = find(p[i])); }
    bool unite(int i, int j) {
        int root_i = find(i), root_j = find(j);
        if (root_i != root_j) { p[root_i] = root_j; return true; }
        return false;
    }
};

void dfs(int u, int p, int d) {
    vis[u] = true;
    depth[u] = d;
    for (auto &edge : adj[u]) {
        int v = edge.first, id = edge.second;
        if (v == p) continue;
        if (!vis[v]) {
            parent_n[v] = u;
            parent_e[v] = id;
            tree_edges.push_back(id);
            is_te[id] = true;
            dfs(v, u, d + 1);
        }
    }
}

void identify_tree(int n, int m, const vector<int>& u, const vector<int>& v) {
    for (int i = 0; i < m; i++) {
        if (is_te[i] || status[i] != -1) continue;

        vector<int> cycle;
        int x = u[i], y = v[i];
        while (x != y) {
            if (depth[x] > depth[y]) { cycle.push_back(parent_e[x]); x = parent_n[x]; }
            else { cycle.push_back(parent_e[y]); y = parent_n[y]; }
        }
        cycle.push_back(i);

        int ref = -1;
        for (int e : cycle) if (status[e] != -1) { ref = e; break; }

		int sres = 0;
		if (ref != -1) sres = status[ref];

        vector<int> results(cycle.size(), -1);
        int mx = -1, mn = 1e9;

        for (int j = 0; j < (int)cycle.size(); j++) {
            int cur = cycle[j];
            if (ref != -1 && status[cur] != -1 && cur != ref) continue;

            vector<int> q;

            for (int te : tree_edges) {
                bool in_c = false;
                for (int ce : cycle) if (ce == te) in_c = true;
                if (!in_c) q.push_back(te);
            }
            for (int k = 0; k < (int)cycle.size(); k++) {
                if (k != j && cycle[k] != i) q.push_back(cycle[k]);
            }
            if (j != (int)cycle.size() - 1) q.push_back(i);

            results[j] = count_common_roads(q);
            mx = max(mx, results[j]);
            mn = min(mn, results[j]);
        }

        for (int j = 0; j < (int)cycle.size(); j++) {
            if (results[j] == -1) continue;
            if (mx == mn) status[cycle[j]] = 0;
            else status[cycle[j]] = (results[j] == mn ? 1 : 0);
        }
    }
    for (int te : tree_edges) if (status[te] == -1) status[te] = 1;
}

vector<int> find_roads(int n, vector<int> u, vector<int> v) {
    int m = u.size();
    tree_edges.clear();
    for (int i = 0; i < n; i++) { adj[i].clear(); vis[i] = false; }
    for (int i = 0; i < m; i++) { status[i] = -1; is_te[i] = false; adj[u[i]].push_back({v[i], i}); adj[v[i]].push_back({u[i], i}); }

    dfs(0, -1, 0);
    identify_tree(n, m, u, v);

    for (int i = 0; i < n; i++) {
        vector<int> cand;
        for (auto &edge : adj[i]) {
            int id = edge.second;
            int other = (u[id] == i ? v[id] : u[id]);
            if (i < other && status[id] == -1) cand.push_back(id);
        }

        auto solve = [&](auto self, vector<int> c) -> void {
            if (c.empty()) return;
            DSU dsu(n);
            for (int id : c) dsu.unite(u[id], v[id]);
            vector<int> q = c;
            int ts = 0;
            for (int te : tree_edges) if (dsu.unite(u[te], v[te])) { q.push_back(te); if (status[te] == 1) ts++; }
            
            int found = count_common_roads(q) - ts;
            if (found == 0) { for (int id : c) status[id] = 0; }
            else if (found == (int)c.size()) { for (int id : c) status[id] = 1; }
            else {
                int mid = c.size() / 2;
                self(self, vector<int>(c.begin(), c.begin() + mid));
                self(self, vector<int>(c.begin() + mid, c.end()));
            }
        };
        solve(solve, cand);
    }

    vector<int> res;
    for (int i = 0; i < m; i++) if (status[i] == 1) res.push_back(i);
    return res;
}

• Subtask 1: 0 / 13
• Subtask 2: 0 / 17
• Subtask 3: 0 / 21
• Subtask 4: 0 / 19
• Subtask 5: 0 / 30