제출 #825027

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
825027		Liudas	수천개의 섬 (IOI22_islands)	C++17	55 / 100	1118 ms	959720 KiB

islands

#include "islands.h"
#include <cassert>
#include <cstdio>
#include <variant>
#include <vector>
#include <map>
#include <set>
#include <algorithm>
#include <iostream>
using namespace std;
bool loop = false;
vector<int> path, lpath;
void dfs(int node, vector<vector<pair<int, int>>> &tree, vector<bool> &vis){
    path.push_back(node);
    if(loop)return;
    if(vis[node] && !loop){
        loop = true;
        lpath = path;
        return;
    }
    vis[node] = true;
    for(auto&[l, r] : tree[node]){
        if(loop)return;
        if(!r){
            r = true;
            dfs(l, tree, vis);
        }
    }
    path.pop_back();
    vis[node] = false;
}
variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V) {
    if (N == 2){
        if(count(U.begin(), U.end(), 0) >= 2 && count(U.begin(), U.end(), 1) >= 1){
            vector<pair<int, int>> ans(M);
            for(int i = 0; i < M; i ++){
                ans[i] = {U[i], i};
            }
            sort(ans.begin(), ans.end());
            vector<int> ret = {ans[0].second, ans.back().second, ans[1].second, ans[0].second, ans.back().second, ans[1].second};
            return ret;
        }
        return false;
    }
    bool N2 = true;
    map<int, int> counts;
    for(int i = 0; i < M; i ++){
        counts[U[i]]++;
        counts[V[i]]++;
    }
    for(int i = 0; i < N; i ++){
        N2 &= (counts[i] == 2 * N - 2);
    }
    if(N2 && N <= 1000){
        vector<vector<pair<int, int>>> tree(N);
        for(int i = 0; i < M; i ++){
            tree[U[i]].push_back({V[i], i});
        }
        for(int i = 0; i < N; i ++){
            sort(tree[i].begin(), tree[i].end());
        }
        vector<int> ret = {tree[0][0].second, tree[1][0].second, tree[0][1].second, tree[2][0].second, tree[1][0].second, tree[0][0].second, tree[2][0].second, tree[0][1].second};
        return ret;
    }
    vector<vector<pair<int,int>>> tree(N);
    bool good = true;
    for(int i = 0; i < M-1; i ++){
        good = V[i] != V[i + 1];
    }
    if(good && N <= 1000){
        for(int i = 0; i < M; i ++){
            tree[U[i]].push_back({V[i], i});
        }
        vector<int> path;
        int id = 0, par = -1;
        bool back = false;
        int NNN = 0;
        while(tree[id].size() < 3 && tree[id].size() > 0 && !back){
            NNN = max(NNN, (int)tree[id].size());
            if(tree[id].size() == 1){
                par = id;
                path.push_back(tree[id][0].second);
                id = tree[id][0].first;
            }
            else{
                if(tree[id][0].first == par){
                    path.push_back(tree[id][1].second);
                    par = id;
                    id = tree[id][1].first;
                }
                else{
                    path.push_back(tree[id][0].second);
                    par = id;
                    id = tree[id][0].first;
                }
            }
            if(id == 0){
                back = true;
            }
        }
        if(!back && tree[0].size() != 0){
            vector<int> mov, ids;
            for(auto[l, r] : tree[id]){
                if (l != par){
                    mov.push_back(l);
                    ids.push_back(r);
                }
                if(mov.size() > 1){
                    break;
                }
            }
            for(int i = 0; i < M; i ++){
                if(mov[0] == U[i] && id == V[i]){
                    ids.insert(ids.begin() + 1, i);
                    break;
                }
            }
            for(int i = 0; i < M; i ++){
                if(mov[1] == U[i] && id == V[i]){
                    ids.push_back(i);
                    break;
                }
            }
            vector<int> gap;
            if(mov[0] == mov[1]){
                gap = {ids[0], ids[1], ids[2], ids[0], ids[1], ids[2]};
            }
            else{
                gap = {ids[0], ids[1], ids[2], ids[3], ids[1], ids[0], ids[3], ids[2]};
            }
            vector<int> legit;
            for(int i : path){
                legit.push_back(i);
            }
            for(int i : gap){
                legit.push_back(i);
            }
            reverse(path.begin(), path.end());
            for(int i : path){
                legit.push_back(i);
            }
            return legit;
        }
        return false;
    }
    for(int i = 0; i < M; i ++){
        tree[U[i]].push_back({V[i], 0});
    }
    vector<bool> vis(N, 0);
    dfs(0, tree, vis);
    if(!loop){
        return false;
    }
    vector<int> arr;
    int id = find(lpath.begin(), lpath.end(), lpath.back()) - lpath.begin();
    int sz = lpath.size();
    vector<int> pre, lap1, lap2, lap1id, lap2id, preid;
    for(int i = 0; i <= id; i ++){
        pre.push_back(lpath[i]);
    }
    for(int j = id; j < sz; j ++){
        lap1.push_back(lpath[j]);
        lap2.push_back(lpath[j]);
    }
    map<pair<int, int>, set<int>> pos; 
    for(int i = 0; i < M; i ++){
        pos[{U[i], V[i]}].insert(i);
    }
    for(int i = 1; i < pre.size(); i++){
        preid.push_back(*pos[{pre[i-1], pre[i]}].begin());
        pos[{pre[i-1], pre[i]}].erase(pos[{pre[i-1], pre[i]}].begin());
    }
    for(int i = 1; i < lap1.size(); i ++){
        lap1id.push_back(*pos[{lap1[i-1], lap1[i]}].begin());
        pos[{lap1[i-1], lap1[i]}].erase(pos[{lap1[i-1], lap1[i]}].begin());
    }
    for(int i = 1; i < lap2.size(); i ++){
        lap2id.push_back(*pos[{lap2[i-1], lap2[i]}].begin());
        pos[{lap2[i-1], lap2[i]}].erase(pos[{lap2[i-1], lap2[i]}].begin());
    }
    for(int i : preid){
        arr.push_back(i);
    }
    for(int j : lap1id){
        arr.push_back(j);
    }
    for(int j : lap2id){
        arr.push_back(j);
    } 
    reverse(preid.begin(), preid.end());
    reverse(lap1id.begin(), lap1id.end());
    reverse(lap2id.begin(), lap2id.end());
    for(int j : lap1id){
        arr.push_back(j);
    }
    for(int j : lap2id){
        arr.push_back(j);
    }
    for(int i : preid){
        arr.push_back(i);
    }
    //cout << lap1id.size() << " " << lap2id.size() << " " << preid.size() <<  endl;
    return arr;
}

컴파일 시 표준 에러 (stderr) 메시지

islands.cpp: In function 'std::variant<bool, std::vector<int, std::allocator<int> > > find_journey(int, int, std::vector<int>, std::vector<int>)':
islands.cpp:169:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  169 |     for(int i = 1; i < pre.size(); i++){
      |                    ~~^~~~~~~~~~~~
islands.cpp:173:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  173 |     for(int i = 1; i < lap1.size(); i ++){
      |                    ~~^~~~~~~~~~~~~
islands.cpp:177:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  177 |     for(int i = 1; i < lap2.size(); i ++){
      |                    ~~^~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 21 / 21
• Subtask 4: 24 / 24
• Subtask 5: 0 / 45