Submission #470917

#	Time	Username	Problem	Language	Result	Execution time	Memory
470917		Tentacleslave	Keys (IOI21_keys)	C++17	0 / 100	1 ms	460 KiB

keys

#include <cstdio>
#include <vector>
#include <deque>
#include <algorithm>
#include <set>

using namespace std;

int increment = 0;
vector<vector<int>> room_group_keys;// --- room group ... data: keys assigned to room group, ordered by key
vector<vector<int>> room_group_rooms;
vector<vector<pair<int, int>>> connector;// --- connector ... data: (outbound room group, key)
vector<int> stack;
vector<int> mutex, depth;

void dfs_init() {
    stack.clear();
    increment = 0;
    mutex.resize(room_group_keys.size());
    for(auto& i : mutex) i = 0;
    depth.resize(room_group_keys.size());
    for(auto& i : depth) i = 0;
}

void dfs(int x) {
    if(mutex[x] == 1) return;
    mutex[x] = 1;
    for(auto i : connector[x]) {
        if(binary_search(room_group_keys[x].begin(), room_group_keys[x].end(), i.second))
            dfs(i.first);
    }
    stack.push_back(x);
}

bool rdfs(int x) {
    if(mutex[x] == 2) return false;
    mutex[x] = 2;
    depth[x] = increment;
    for(auto i : connector[x]) {
        if(binary_search(room_group_keys[i.first].begin(), room_group_keys[i.first].end(), i.second))
            rdfs(i.first);
    }
    return true;
}

void dfs_final(int x, vector<int>& logging) {
    if(mutex[x] == 1)
        return;
    mutex[x] = 1;
    for(auto i : connector[x]) {
        if(binary_search(room_group_keys[x].begin(), room_group_keys[x].end(), i.second)) {
            if(x != i.first)
                logging[x] = false;
            dfs_final(i.first, logging);
        }
    }
}

vector<int> find_reachable_internal() {
    int prev = room_group_keys.size();
    // To-do: construct SCC
    dfs_init();
    for(int i = 0; i < room_group_keys.size(); i++) dfs(i);
    while(stack.size()) {
        int top = stack.back();
        if(rdfs(top))
            increment++;
        stack.pop_back();
    }
    // Report result (if SCC is equal with graph)
    if(prev == increment) {
        dfs_init();
        vector<int> logging;
        logging.resize(prev, true);
        for(int i = 0; i < prev; i++)
            dfs_final(i, logging);
        
        int min_size = 1e9, sum = 0;
        for(int i = 0; i < prev; i++) {
            int s = room_group_rooms[i].size();
            sum += s;
            if(min_size > s && logging[i])
                min_size = s;
        }
        vector<int> ans;
        ans.resize(sum, 0);

        
        for(int i = 0; i < prev; i++) {
            int s = room_group_rooms[i].size();
            if(min_size != s || !logging[i])
                continue;
            for(auto j : room_group_rooms[i]) {
                ans[j] = 1;
            }
        }
        return ans;
    }

    // Query (if SCC is smaller than graph)
    vector<vector<int>> new_room_group_keys;
    vector<vector<int>> new_room_group_rooms;
    vector<vector<pair<int, int>>> new_connector;
    new_room_group_keys.resize(increment, {});
    new_room_group_rooms.resize(increment, {});
    new_connector.resize(increment, {});
    for(int i = 0; i < prev; i++) {
        for(auto j : room_group_keys[i])
            new_room_group_keys[depth[i]].push_back(j);
        for(auto j : room_group_rooms[i])
            new_room_group_rooms[depth[i]].push_back(j);
        for(auto j : connector[i])
            new_connector[depth[i]].push_back({depth[j.first], j.second});
    }
    for(int i = 0; i < increment; i++) {
        std::sort(new_room_group_keys[i].begin(), new_room_group_keys[i].end());
        if(new_room_group_keys[i].size())
            new_room_group_keys[i].erase(unique(new_room_group_keys[i].begin(), new_room_group_keys[i].end()), new_room_group_keys[i].end());
        std::sort(new_connector[i].begin(), new_connector[i].end());
        if(new_room_group_keys[i].size())
            new_connector.erase(unique(new_connector.begin(), new_connector.end()), new_connector.end());
    }
    room_group_keys = new_room_group_keys;
    room_group_rooms = new_room_group_rooms;
    connector = new_connector;
    //return {};
    return find_reachable_internal();
}

vector<int> find_reachable(vector<int> r, vector<int> u, vector<int> v, vector<int> c) {
    connector.resize(r.size(), {});
    for(int i = 0; i < r.size(); i++) {
        room_group_keys.push_back({r[i]});
        room_group_rooms.push_back({i});
    }
    for(int i = 0; i < u.size(); i++) {
        connector[u[i]].push_back({v[i], c[i]});
        connector[v[i]].push_back({u[i], c[i]});
    }
    for(int i = 0; i < r.size(); i++)
        std::sort(room_group_keys[i].begin(), room_group_keys[i].end());
    connector.resize(r.size());
    return find_reachable_internal();
}

Compilation message (stderr)

keys.cpp: In function 'std::vector<int> find_reachable_internal()':
keys.cpp:63:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |     for(int i = 0; i < room_group_keys.size(); i++) dfs(i);
      |                    ~~^~~~~~~~~~~~~~~~~~~~~~~~
keys.cpp: In function 'std::vector<int> find_reachable(std::vector<int>, std::vector<int>, std::vector<int>, std::vector<int>)':
keys.cpp:132:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  132 |     for(int i = 0; i < r.size(); i++) {
      |                    ~~^~~~~~~~~~
keys.cpp:136:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  136 |     for(int i = 0; i < u.size(); i++) {
      |                    ~~^~~~~~~~~~
keys.cpp:140:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  140 |     for(int i = 0; i < r.size(); i++)
      |                    ~~^~~~~~~~~~

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