Submission #561277

#	Time	Username	Problem	Language	Result	Execution time	Memory
561277		messiuuuuu	Joker (BOI20_joker)	C++14	0 / 100	137 ms	10052 KiB

Joker

#include<bits/stdc++.h>
#define task "F"
#define ll long long
#define ld long double
#define fi first
#define se second
#define pb push_back
using namespace std;
const int MAXN = 2e5 + 5;
const ll INF = 1e18 + 5;

int n, m, q;
pair<int, int> es[MAXN];

void Input()
{
    cin >> n >> m >> q;
    for (int i = 1; i <= m; i++)
        cin >> es[i].fi >> es[i].se;
}

struct TRback
{
    int u, lu, v, lv, parev;
};

stack<TRback> Q;

int lab[MAXN], f[MAXN];
bool pare[MAXN];

pair<int, int> FindSet(int u)
{
    bool w = 0;
    while (lab[u] > 0)
    {
        w ^= pare[u];
        u = lab[u];
    }
    return {u, w};
}

bool Unite(int u, int v)
{
    auto pu = FindSet(u);
    auto pv = FindSet(v);
    if (pu.fi == pv.fi)
    {
        return (pu.se != pv.se);
    }
    if (lab[pu.fi] > lab[pv.fi])
        swap(pu, pv);
    u = pu.fi;
    v = pv.fi;
    Q.push({u, lab[u], v, lab[v], pare[v]});
    lab[u] += lab[v];
    lab[v] = u;
    pare[v] = pu.se ^ pv.se ^ 1;
    return 1;
}

void rollback(int sz)
{
    while (Q.size() > sz)
    {
        auto p = Q.top();
        Q.pop();
        lab[p.u] = p.lu;
        lab[p.v] = p.lv;
        pare[p.v] = p.parev;
    }
}

void Dnc(int l, int r, int pl, int pr)
{
    if (l > r)
        return;
    int mid = (l + r) / 2;
    int s = Q.size();
    bool kt = 1;
    for (int i = l; i <= mid; i++)
    {
        if (!Unite(es[i].fi, es[i].se))
        {
            kt = 0;
            break;
        }
    }
    if (kt)
    {
        int s1 = Q.size();
        for (int i = min(m, pr); i >= max(mid + 1, pl); i--)
        {
            if (!Unite(es[i].fi, es[i].se))
            {
                f[mid] = i;
                break;
            }
        }

        //if (mid == 1)
         //   cerr << f[mid] << '\n';

        rollback(s1);
        Dnc(mid + 1, r, f[mid], pr);
    }
    rollback(s);
    for (int i = f[mid] + 1; i <= pr; i++)
        Unite(es[i].fi, es[i].se);
    Dnc(l, mid - 1, pl, f[mid]);
    rollback(s);
}

void Solve()
{
    memset(lab, -1, sizeof(lab));
    fill(f + 1, f + 1 + m, m + 1);

    Dnc(1, m, 1, m);

    /*
    for (int i = 1; i <= m; i++)
        cerr << f[i] << ' ';
    cerr << '\n';
    */

    while (q-- > 0)
    {
        int l, r;
        cin >> l >> r;
        l--;
        r++;
        cout << (r <= f[l] ? "YES\n" : "NO\n");
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    //freopen(task".INP","r",stdin);
    //freopen(task".OUT","w",stdout);
    Input();
    Solve();
}

Compilation message (stderr)

Joker.cpp: In function 'void rollback(int)':
Joker.cpp:64:21: warning: comparison of integer expressions of different signedness: 'std::stack<TRback>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   64 |     while (Q.size() > sz)
      |            ~~~~~~~~~^~~~

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