Submission #1350999

#TimeUsernameProblemLanguageResultExecution timeMemory
1350999rahidilbayramliEvent Hopping (BOI22_events)C++20
100 / 100
187 ms27228 KiB
#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define vl vector<ll>
#define vi vector<int>
#define pb push_back
#define sz(v) (ll)(v.size())
#define f first
#define s second
#define pll pair<ll, ll>
#define pii pair<int, int>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
using namespace std;
const ll sz = 1e5+5;
ll p[30][sz];
bool cmp(pair<pll, ll> p1, pair<pll, ll> p2)
{
    if(p1.f.s != p2.f.s)
        return (p1.f.s < p2.f.s);
    return (p1.f.f < p2.f.f);
}
void solve()
{
    ll n, q, i, j;
    cin >> n >> q;
    pair<pll, ll> p1[n+5];
    for(i = 1; i <= n; i++)
    {
        cin >> p1[i].f.f >> p1[i].f.s;
        p1[i].s = i;
    }
    sort(p1+1, p1+n+1, cmp);
    vl v;
    for(i = 1; i <= n; i++)
    {
        while(sz(v) && p1[v.back()].f.f > p1[i].f.f)
            v.pop_back();
        v.pb(i);
        ll l = 0, r = sz(v) - 1, bst = sz(v) - 1;
        while(l <= r)
        {
            ll mid = (l + r) / 2;
            if(p1[v[mid]].f.s >= p1[i].f.f)
            {
                bst = mid;
                r = mid - 1;
            }
            else
                l = mid + 1;
        }
        p[0][i] = v[bst];
    }
    for(i = 1; i < 21; i++)
    {
        for(j = 1; j <= n; j++)
            p[i][j] = p[i-1][p[i-1][j]];
    }
    map<ll, ll>mp;
    for(i = 1; i <= n; i++)
        mp[p1[i].s] = i;
    while(q--)
    {
        ll a, b;
        cin >> a >> b;
        a = mp[a];
        b = mp[b];
        if(a == b)
        {
            cout << "0\n";
            continue;
        }
        if(p1[b].f.f <= p1[a].f.s && p1[a].f.s <= p1[b].f.s)
        {
            cout << "1\n";
            continue;
        }
        ll res = 0;
        for(ll i = 20; i >= 0; i--)
        {
            if(p1[p[i][b]].f.f <= p1[a].f.s)
                continue;
            res += (1 << i);
            b = p[i][b];
        }
        ll t = p[0][b];
        if(p1[t].f.f <= p1[a].f.s && p1[a].f.s <= p1[t].f.s)
            cout << res + 2 << "\n";
        else
            cout << "impossible\n";
    }
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    ll tests = 1;
    //cin >> tests;
    while(tests--)
    {
        solve();
    }
}
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