제출 #850829

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
850829		tvladm2009	Event Hopping (BOI22_events)	C++17	100 / 100	614 ms	85472 KiB

events

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
const int N = (int) 1e5 + 7;
int n;
int q;

struct T {
  int l;
  int r;
  int ind;
};

bool operator < (T a, T b) {
  if (a.r != b.r) {
    return a.r < b.r;
  } else {
    return a.l < b.l;
  }
}

T a[N];
int l[N];
int r[N];
int where[N];

int bs(int x) {
  int low = 1, high = n, sol = 0;
  while (low <= high) {
    int mid = (low + high) / 2;
    if (a[mid].r <= x) {
      sol = mid;
      low = mid + 1;
    } else {
      high = mid - 1;
    }
  }
  return sol;
}

pair<int, int> unite(pair<int, int> a, pair<int, int> b) {
  return {min(a.first, b.first), max(a.second, b.second)};
}

const int K = 20;
pair<int, int> tab[K][N];
pair<int, int> segt[K][4 * N];

void build(int v, int tl, int tr, int k) {
  if (tl == tr) {
    segt[k][v] = tab[k][tl];
  } else {
    int tm = (tl + tr) / 2;
    build(2 * v, tl, tm, k);
    build(2 * v + 1, tm + 1, tr, k);
    segt[k][v] = unite(segt[k][2 * v], segt[k][2 * v + 1]);
  }
}

pair<int, int> get(int v, int tl, int tr, int l, int r, int k) {
  if (l <= tl && tr <= r) {
    return segt[k][v];
  }
  int tm = (tl + tr) / 2;
  if (l <= tm && r <= tm) {
    return get(2 * v, tl, tm, l, r, k);
  }
  if (tm + 1 <= l && tm + 1 <= r) {
    return get(2 * v + 1, tm + 1, tr, l, r, k);
  }
  return unite(get(2 * v, tl, tm, l, tm, k), get(2 * v + 1, tm + 1, tr, tm + 1, r, k));
}

pair<int, int> get(int l, int r, int k) {
  return get(1, 1, n, l, r, k);
}

void build(int k) {
  build(1, 1, n, k);
}

pair<int, int> go_up(pair<int, int> cur, int k) {
  return get(cur.first, cur.second, k);
}

int main() {
  ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

  // freopen ("input", "r", stdin);

  cin >> n >> q;
  for (int i = 1; i <= n; i++) {
    cin >> a[i].l >> a[i].r;
    a[i].ind = i;
  }
  sort(a + 1, a + n + 1);
  for (int i = 1; i <= n; i++) {
    where[a[i].ind] = i;
  }
  for (int i = 1; i <= n; i++) {
    l[i] = bs(a[i].l - 1) + 1;
    r[i] = bs(a[i].r);
    tab[0][i] = {l[i], r[i]};
  }
  build(0);
  for (int k = 1; k < K; k++) {
    for (int i = 1; i <= n; i++) {
      tab[k][i] = go_up(tab[k - 1][i], k - 1);
    }
    build(k);
  }

  for (int iq = 1; iq <= q; iq++) {
    int ff, ss;
    cin >> ff >> ss;
    ff = where[ff];
    ss = where[ss];
    int sol = 1;
    pair<int, int> now = {ss, ss};
    pair<int, int> nxt = go_up(now, K - 1);
    if (nxt.second < ff || nxt.first > ff) {
      cout << "impossible\n";
      continue;
    }
    if (ff == ss) {
      cout << "0\n";
      continue;
    } 
    for (int k = K - 1; k >= 0; k--) {
      pair<int, int> nxt = go_up(now, k);
      if (nxt.second < ff || nxt.first > ff) {
        sol += (1 << k);
        now = nxt;
      }
    }
    cout << sol << "\n";
  }
  return 0;
}

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