Submission #1158036

#	Time	Username	Problem	Language	Result	Execution time	Memory
1158036		Mher777	Event Hopping (BOI22_events)	C++20	30 / 100	273 ms	82084 KiB

events

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <iomanip>
#include <array>
#include <string>
#include <algorithm>
#include <cmath>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <bitset>
#include <list>
#include <iterator>
#include <numeric>
#include <complex>
#include <utility>
#include <random>
#include <cassert>
#include <fstream>
using namespace std;
mt19937 rnd(time(nullptr));

/* -------------------- Typedefs -------------------- */

typedef int itn;
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef float fl;
typedef long double ld;

/* -------------------- Usings -------------------- */

using vi = vector<int>;
using vll = vector<ll>;
using mii = map<int, int>;
using mll = map<ll, ll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

/* -------------------- Defines -------------------- */

#define ff first
#define ss second
#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define mpr make_pair
#define yes cout<<"Yes\n"
#define no cout<<"No\n"
#define all(x) (x).begin(), (x).end()
#define USACO freopen("feast.in", "r", stdin); freopen("feast.out", "w", stdout);

/* -------------------- Constants -------------------- */

const int dx[8] = { -1, 0, 1, 0, -1, -1, 1, 1 };
const int dy[8] = { 0, -1, 0, 1, -1, 1, -1, 1 };
const int MAX = int(1e9 + 5);
const ll MAXL = ll(1e18) + 5ll;
const ll MOD = ll(1000000007);
const ll MOD2 = ll(998244353);

/* -------------------- Functions -------------------- */

void fastio() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
}

void precision(int x) {
    cout.setf(ios::fixed | ios::showpoint);
    cout.precision(x);
}

ll gcd(ll a, ll b) {
    if (a == 0 || b == 0) return(max(a, b));
    while (b) {
        a %= b;
        swap(a, b);
    }
    return a;
}

ll lcm(ll a, ll b) {
    return a / gcd(a, b) * b;
}

ll range_sum(ll a, ll b) {
    if (a > b) return 0ll;
    ll dif = a - 1, cnt = b - a + 1;
    ll ans = ((b - a + 1) * (b - a + 2)) / 2;
    ans += ((b - a + 1) * dif);
    return ans;
}

string dec_to_bin(ll a) {
    string s = "";
    for (ll i = a; i > 0; ) {
        ll k = i % 2;
        i /= 2;
        char c = k + 48;
        s += c;
    }
    if (a == 0) {
        s = "0";
    }
    reverse(all(s));
    return s;
}

ll bin_to_dec(string s) {
    ll num = 0;
    for (int i = 0; i < s.size(); i++) {
        num *= 2ll;
        num += (s[i] - '0');
    }
    return num;
}

ll factorial_by_mod(ll n, ll mod) {
    ll ans = 1;
    ll num;
    for (ll i = 1; i <= n; ++i) {
        num = i % mod;
        ans *= num;
        ans %= mod;
    }
    return ans;
}

bool isPrime(ll a) {
    if (a == 1) return false;
    for (ll i = 2; i * i <= a; i++) {
        if (a % i == 0) return false;
    }
    return true;
}

ll binpow(ll a, ll b) {
    if (!a) return 0;
    ll ans = 1;
    while (b) {
        if (b & 1) {
            ans *= a;
        }
        b >>= 1;
        a *= a;
    }
    return ans;
}

ll binpow_by_mod(ll a, ll b, ll mod) {
    if (!a) return 0;
    ll ans = 1;
    while (b) {
        if (b & 1) {
            ans *= a;
            ans %= mod;
        }
        b >>= 1;
        a *= a;
        a %= mod;
    }
    return ans;
}

/* -------------------- Solution -------------------- */

const int N = 200005, M = 30;
int up[N][M];
pii ac[N];
vector<pair<pii, int>> a;
pii st[N][M], till[N];
unordered_map<int, int> id;
int n, q, m, lg;

void bld_sparse() {
    for (int l = 1; l <= (int)log2(m); ++l) {
        for (int i = 1; i + (1 << l) - 1 <= m; ++i) {
            st[i][l] = max(st[i][l - 1], st[i + (1 << (l - 1))][l - 1]);
        }
    }
}

pii qry(int l, int r) {
    int lgx = log2(r - l + 1);
    return max(st[l][lgx], st[r - (1 << lgx) + 1][lgx]);
}

bool check(int ls, int rs, int le, int re) {
    return (le <= rs && re >= rs);
}

void slv() {
    cin >> n >> q;
    a.resize(n + 1);
    lg = log2(n);
    set<int> stx;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i].ff.ff >> a[i].ff.ss;
        a[i].ss = i;
        stx.insert(a[i].ff.ff);
        stx.insert(a[i].ff.ss);
    }
    for (auto elem : stx) {
        id[elem] = ++m;
    }
    for (int i = 1; i <= n; ++i) {
        a[i].ff.ff = id[a[i].ff.ff];
        a[i].ff.ss = id[a[i].ff.ss];
        ac[i] = a[i].ff;
        till[a[i].ff.ff] = { a[i].ff.ss, i };
        swap(a[i].ff.ff, a[i].ff.ss);
    }
    pii last = { 0,0 };
    for (int i = 1; i <= m; ++i) {
        last = max(last, till[i]);
        st[i][0] = last;
    }
    bld_sparse();
    sort(all(a));
    for (int i = n; i >= 1; --i) {
        int ind = a[i].ss;
        pii opt = qry(a[i].ff.ss, a[i].ff.ff);
        up[ind][0] = (opt.ff == a[i].ff.ff ? ind : opt.ss);
        for (int l = 1; l <= lg; ++l) {
            up[ind][l] = up[up[ind][l - 1]][l - 1];
        }
    }
    while (q--) {
        int s, e;
        cin >> s >> e;
        if (s == e) {
            cout << 0 << '\n';
            continue;
        }
        if (ac[e].ss < ac[s].ff) {
            cout << "impossible\n";
            continue;
        }
        int ls = ac[s].ff, rs = ac[s].ss;
        int le = ac[e].ff, re = ac[e].ss;
        int ans = 0;
        for (int l = lg; l >= 0; --l) {
            int new_rs = ac[up[s][l]].ss;
            if (new_rs >= re) continue;
            ans += (1 << l);
            rs = new_rs;
            s = up[s][l];
        }
        int maxr = qry(ls, rs).ff;
        if (check(ls, rs, le, re)) {
            cout << ans + 1 << '\n';
            continue;
        }
        if (maxr == re) {
            cout << ans + 2 << '\n';
            continue;
        }
        cout << "impossible\n";
    }
}

void cs() {
    int tstc = 1;
    //cin >> tstc;
    while (tstc--) {
        slv();
    }
}

void precalc() {
    return;
}

int main() {
    fastio();
    precalc();
    //precision(0);
    cs();
    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 20 / 20
• Subtask 6: 0 / 30