제출 #798398

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
798398		PixelCat	Simurgh (IOI17_simurgh)	C++14	30 / 100	198 ms	4020 KiB

simurgh

#include "simurgh.h"

#ifdef NYAOWO
#include "grader.cpp"
#endif

#include <bits/stdc++.h>
#define For(i, a, b) for(int i = a; i <= b; i++)
#define Forr(i, a, b) for(int i = a; i >= b; i--)
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define sz(x) ((int)x.size())
#define eb emplace_back
// #define int LL
using namespace std;
using i32 = int32_t;
using LL = long long;
using pii = pair<int, int>;

const int MAXN = 500;

vector<pii> adj[MAXN + 10];  // { node, edge id }

struct Tree {
    set<int> edge;
    set<int> suseid;
    set<int> egg;
    set<int> epote;
    int par[MAXN + 10];
    int dep[MAXN + 10];
    int peid[MAXN + 10];
    bool good[MAXN + 10];
    bool sussy[MAXN + 10];
    vector<int> get_edges() {
        vector<int> ids;
        for(auto &i:edge) ids.eb(i);
        return ids;
    }
    int query() {
        // cerr << "query: ";
        // out();
        return count_common_roads(get_edges());
    }
    void dfs(int x, int p, int d, int pe, bool tree_edge_only = true) {
        if(p < 0) {
            memset(dep, 0, sizeof(dep));
        }
        par[x] = p;
        dep[x] = d;
        peid[x] = pe;
        good[x] = !suseid.count(pe);
        sussy[x] = !good[x];
        for(auto &i:adj[x]) if(i.F != p && dep[i.F] == 0) {
            if(tree_edge_only && !edge.count(i.S)) continue;
            else if(!tree_edge_only) {
                edge.insert(i.S);
                suseid.insert(i.S);
            }
            dfs(i.F, x, d + 1, i.S, tree_edge_only);
            good[x] = good[x] && good[i.F];
            sussy[x] = sussy[x] && good[i.F];
        }
    }
    void collect(int x, int p, set<int> &subtree) {
        subtree.insert(x);
        for(auto &i:adj[x]) if(i.F != p && edge.count(i.S)) {
            collect(i.F, x, subtree);
        }
    }
    void build_tree(int N) {
        For(_, 1, N - 1) {
            dfs(0, -1, 1, -1);
            // For(i, 0, N - 1) cerr << par[i] << " \n"[i == N - 1];
            // For(i, 0, N - 1) cerr << peid[i] << " \n"[i == N - 1];

            int x = -1;
            For(i, 0, N - 1) if(sussy[i]) x = i;
            assert(x >= 0);
            suseid.erase(peid[x]);
            int cnt;

            set<int> subtree;
            collect(x, par[x], subtree);
            vector<int> eids;
            for(auto &a:subtree) for(auto &e:adj[a]) {
                if(subtree.count(e.F) || egg.count(e.S)) continue;
                // if(epote.count(e.S)) {
                //     edge.erase(peid[x]);
                //     edge.insert(e.S);
                //     goto FOUND;
                // }
                eids.eb(e.S);
            }
            
            cnt = query();
            edge.erase(peid[x]);
            For(i, 0, sz(eids) - 1) {
                edge.insert(eids[i]);
                int cnt2 = query();
                if(cnt < cnt2) {
                    // For(j, 0, i - 1) egg.insert(eids[j]);
                    // egg.insert(peid[x]);
                    // epote.insert(eids[i]);
                    goto FOUND;
                } else if(cnt > cnt2) {
                    // For(j, 0, i - 1) epote.insert(eids[j]);
                    // epote.insert(peid[x]);
                    // egg.insert(eids[i]);
                    edge.erase(eids[i]);
                    edge.insert(peid[x]);
                    goto FOUND;
                }
                edge.erase(eids[i]);
            }
            edge.insert(peid[x]);
            FOUND:;
            out();
        }
    }
    void out() {
        #ifdef NYAOWO
        cerr << "tree: ";
        for(auto &i:get_edges()) {
            cerr << i << " ";
        }
        cerr << "\n";
        #endif
    }
} tr;

vector<int> find_roads(int N, vector<int> U, vector<int> V) {
    int M = sz(U);
    For(i, 0, M - 1) {
        adj[U[i]].eb(V[i], i);
        adj[V[i]].eb(U[i], i);
    }
    tr.dfs(0, -1, 1, -1, false);
    tr.build_tree(N);
    return tr.get_edges();

    // vector<int> r(n - 1);
    // for(int i = 0; i < n - 1; i++)
    //     r[i] = i;
    // int common = count_common_roads(r);
    // if(common == n - 1)
    //     return r;
    // r[0] = n - 1;
    // return r;
}

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