Submission #1013820

#	Time	Username	Problem	Language	Result	Execution time	Memory
1013820		Mr_Husanboy	Joker (BOI20_joker)	C++17	100 / 100	214 ms	35632 KiB

Joker

//#pragma GCC optimize("Ofast,O3")
//#pragma GCC target("avx,avx2")
#include <bits/stdc++.h>
using namespace std;



#ifdef LOCAL
#include "debugger.cpp"
#else
#define debug(...)
#endif
template<class T>
int len(T &a){
    return a.size();
}

using ll = long long;
using pii = pair<int,int>;
#define all(a) (a).begin(), (a).end()
#define ff first
#define ss second
string fileio = "";

mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
const int MOD = 1e9 + 7;
const int inf = 1e9;
const ll infl = 1e18;
const int maxn = 1e5 + 1;



struct DSU_roll_back{
    int n;
    vector<int> p;
    vector<int> sz;
    vector<int> d;
    vector<pair<int &, int>> his;
    int bip = 1;

    DSU_roll_back (int n) : n(n), p(n), sz(n), d(n){
        for(int i = 0; i < n;i ++) p[i] = i, sz[i] = 1;
    }

    int get(int x, int &col){
        col ^= d[x];
        return p[x] == x ? x : get(p[x], col);
    }

    void unite(int a, int b){
        if(bip == 0){
            return;
        }
        int ca = 0, cb = 0;
        a = get(a, ca), b = get(b, cb);
        if(a == b){
            if(ca == cb){
                his.push_back({bip, bip});
                bip = 0;
            }
            return;
        }
        if(sz[a] < sz[b]) swap(a, b);
        his.push_back({sz[a], sz[a]});
        his.push_back({p[b], p[b]});
        his.push_back({d[b], d[b]});
        d[b] = ca == cb;
        sz[a] += sz[b];
        p[b] = a;
    }

    int snap(){
        return his.size();
    }

    void roll_back(int until){
        while(len(his) > until){
            his.back().ff = his.back().ss;
            his.pop_back();
        }
    }
};

void solve(){
    int n, m, q; cin >> n >> m >> q;

    vector<int> a(m + 1), b(m + 1);

    for(int i = 1; i <= m; i ++){
        cin >> a[i] >> b[i]; a[i] --; b[i] --;
    }
    vector<vector<pair<int,int>>> qu(m + 1);
    for(int i = 0; i < q; i++){
        int l, r; cin >> l >> r;
        qu[l].push_back({r, i});
    }

    DSU_roll_back ds(n);
    vector<int> ans(q);


    auto calc = [&](auto &calc, int l, int r, int optr)->void{
        if(l > r) return;
        int m = (l + r) / 2;
        int lsz = ds.snap();
        for(int i = l; i < m; i ++) ds.unite(a[i], b[i]);
        int optm = optr;
        while(optr >= m && ds.bip){
            optm --;
            ds.unite(a[optm], b[optm]);
        }
        for(auto [rig, j] : qu[m]){
            ans[j] = rig < optm;
        }

        ds.roll_back(lsz);

        for(int i = optr - 1; i >= optm; i --){
            ds.unite(a[i], b[i]);
        }
        calc(calc, l, m - 1, optm);
        ds.roll_back(lsz);
        for(int i = l; i <= m; i ++){
            ds.unite(a[i], b[i]);
        }
        calc(calc, m + 1, r, optr);
        ds.roll_back(lsz);
    };

    calc(calc, 1, m, m + 1);
    for(auto u : ans) cout << (u ? "YES\n" : "NO\n");
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    auto start = chrono::high_resolution_clock::now();
    #ifndef LOCAL
    if(fileio.size()){
        freopen((fileio + ".in").c_str(), "r", stdin);
        freopen((fileio + ".out").c_str(), "w", stdout);
    }
    #endif
    int testcases = 1;
    #ifdef Tests
    cin >> testcases;
    #endif
    while(testcases --){
        solve();
        if(testcases) cout << '\n';
        #ifdef LOCAL
        else cout << '\n';
        cout << "_________________________" << endl;
        #endif
    }
    #ifdef LOCAL
    auto duration = chrono::duration_cast<chrono::microseconds>(chrono::high_resolution_clock::now() - start);
    
    cout << "time: " << (double)duration.count()/1000.0 << " milliseconds" << endl;
    #endif
    return 0;
}

Compilation message (stderr)

Joker.cpp: In function 'int main()':
Joker.cpp:136:10: warning: variable 'start' set but not used [-Wunused-but-set-variable]
  136 |     auto start = chrono::high_resolution_clock::now();
      |          ^~~~~
Joker.cpp:139:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  139 |         freopen((fileio + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Joker.cpp:140:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  140 |         freopen((fileio + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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