Submission #765300

#	Time	Username	Problem	Language	Result	Execution time	Memory
765300		canadavid1	Joker (BOI20_joker)	C++14	0 / 100	2035 ms	9248 KiB

Joker

#include <bits/stdc++.h>


using namespace std;

vector<bool> diff;
vector<int> p;
vector<int> siz;
vector<pair<int,int>> history;
vector<bool> legal = {1};
pair<int,bool> find(int a,bool len=0)
{
    if (p[a] == -1) return {a,len};
    return find(p[a],len^diff[a]); // no path compression
}

bool unite(int a,int b) // true if works, false elsewise
{
    auto av = find(a);
    auto bv = find(b);
    if (av.first == bv.first) 
    {
        history.push_back({-1,-1});
        legal.push_back(legal.back()&(av.second!=bv.second));
        return legal.back();
        
    }
    
    if (siz[av.first] > siz[bv.first]) swap(av,bv);
    // b > a
    p[av.first] = bv.first;
    siz[bv.first] += siz[av.first];
    if (av.second == bv.second) diff[av.first] = true;
    history.push_back({av.second,bv.second});
    legal.push_back(legal.back());
    return legal.back();
}
bool undo()
{
    auto ab = history.back(); history.pop_back();
    legal.pop_back();
    if (ab.first == -1) return legal.back();
    p[ab.first] = -1;
    diff[ab.first] = false;
    siz[ab.second] -= siz[ab.first];
    return legal.back();
}
inline bool works()
{
    return legal.back();
}
vector<pair<int,int>> edge;
inline void addEdge(int idx)
{
    unite(edge[idx].first,edge[idx].second);
}


vector<pair<int,pair<int,int>>> query;
vector<bool> queryvalid;
int N,M,Q,added;
int main()
{
    cin >> N >> M >> Q;
    diff.assign(N+1,false);
    p.assign(N+1,-1);
    siz.assign(N+1,1);
    queryvalid.assign(Q,false);
    edge.push_back({0,0});
    for(int i = 0; i < M; i++)
    {
        int l,r;
        cin >> l >> r;
        edge.push_back({l,r});     
    }
    for(int i = 0; i < Q; i++)
    {
        int l,r;
        cin >> l >> r;
        query.push_back({i,{l,r}});
    }
    const int TOP = M;
    sort(query.begin(),query.end(),[](auto a, auto b){return a.second.second > b.second.second;});
    for(int i = M; i > TOP; i--) addEdge(i);
    while(query.size() && query.back().second.second <= TOP)
    {
        for(int i = TOP; i > query.back().second.second; i--) addEdge(i);
        for(int i = 1; i < query.back().second.first; i--) addEdge(i);
        queryvalid[query.back().first] = works();
        for(int i = 1; i < query.back().second.first; i--) undo();
        for(int i = TOP; i > query.back().second.second; i--) undo();   
        query.pop_back();     
    }
    for(int i = M; i > TOP; i--) undo();
    for (auto &&i : queryvalid)
    {
        cout << (i ? "NO\n" : "YES\n");
    }

/*
    vector<vector<int>> neigh(N+1);
    vector<pair<int,int>> edge;
    for(int i = 0; i < N; i++)
    {
        int u,v;
        cin >> u >> v;
        neigh[u].push_back(v);
        neigh[v].push_back(u);
        edge.push_back({u,v});
    }
    vector<pair<int,int>> query(Q);
    int l;
    for (auto &&r : query) cin >> l >> r.first;
    for(int i = 0; i < Q; i++) query[i].second = i;
    sort(query.begin(),query.end());
    vector<bool> result;
    int s;
    while(query.size())
    {

    }*/
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 8
• Subtask 3: 0 / 25
• Subtask 4: 0 / 10
• Subtask 5: 0 / 22
• Subtask 6: 0 / 29