제출 #216496

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
216496		emil_physmath	Simurgh (IOI17_simurgh)	C++17	30 / 100	372 ms	38648 KiB

simurgh

#include "simurgh.h"
#include <algorithm>
#include <iostream>
#include <vector>
#include <map>
using namespace std;
#define query count_common_roads
const int maxN = 500;
struct Jmp
{
    int to, ind;
    operator int&() { return to; }
    operator const int&() const { return to; }
};

int in[maxN], out[maxN];
Jmp par[maxN];
int gold[maxN * maxN];
vector<int> dfsq;
vector<Jmp> nei[maxN];
vector<int> same[maxN * maxN];
Jmp fup[maxN];

map<vector<int>, int> cache;
int Query(vector<int> q)
{
    auto it = cache.find(q);
    if (it != cache.end()) return it->second;
    return cache[q] = query(q);
}
inline bool Upper(int u, int v) { return in[u] <= in[v] && out[u] >= out[v]; }
bool used[maxN];
void DFS(int v, Jmp p)
{
    // cerr << "v: " << v << '\n';
    static int time = 0;
    used[v] = true;
    in[v] = ++time;
    par[v] = p;
    fup[v] = {-1, -1};
    for (Jmp to: nei[v])
        if (!used[to])
        {
            dfsq.push_back(to.ind);
            DFS(to, {v, to.ind});
            if (p != -1)
                if (fup[v] == -1 || (fup[to] != -1 && in[fup[to]] <= in[fup[v]]))
                    fup[v] = fup[to];
        }
        else if (to != p && p != -1)
            if (fup[v] == -1 || in[to] <= in[fup[v]])
                fup[v] = to;
    out[v] = time;
}

void DFS1(int v)
{
    for (int to: same[v])
        if (gold[to] == -1)
        {
            gold[to] = gold[v];
            DFS1(to);
        }
}
vector<int> find_roads(int n, vector<int> us, vector<int> vs)
{
    int m = us.size();
    fill(gold, gold + m, -1);
    for (int i = 0; i < m; ++i)
    {
        nei[us[i]].push_back({vs[i], i});
        nei[vs[i]].push_back({us[i], i});
    }
    DFS(0, {-1, -1});
    // for (int i = 0; i < n; ++i)
        // cerr << "fup[" << i << "] = " << fup[i].to << '\n';
    int dfsans = Query(dfsq);
    for (int i = 0; i < m; ++i)
        if (in[us[i]] > in[vs[i]])
            swap(us[i], vs[i]);
    for (int i = 0; i < m; ++i)
    {
        int u = us[i], v = vs[i];
        if (fup[v] == -1 || in[fup[v]] > in[u]) // Is a birdge.
        {
            gold[i] = 1;
            continue;
        }
        if (par[v] == u) continue;
        while (true)
        {
            int backe = i, dfse = par[v].ind;
            // cerr << dfse << ' ' << backe << '\n';
            int j = find(dfsq.begin(), dfsq.end(), dfse) - dfsq.begin();
            dfsq[j] = backe;
            int curans = Query(dfsq);
            if (curans == dfsans)
            {
                same[backe].push_back(dfse);
                same[dfse].push_back(backe);
            }
            else if (curans > dfsans)
                gold[backe] = 1, gold[dfse] = 0;
            else
                gold[backe] = 0, gold[dfse] = 1;
            dfsq[j] = dfse;
            if ((v = par[v]) == u) break;
        }
    }
    for (int i = 0; i < m; ++i)
        if (gold[i] != -1)
            DFS1(i);
    vector<int> ans;
    for (int i = 0; i < m; ++i)
        if (gold[i] == 1)
            ans.push_back(i);
    return ans;
}

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