Submission #623105

#	Time	Username	Problem	Language	Result	Execution time	Memory
623105		slime	Event Hopping (BOI22_events)	C++14	100 / 100	327 ms	58984 KiB

events

#include "bits/stdc++.h"
using namespace std;
#define int long long
const int MAXN = 3e5 + 10;
const int MOD = 998244353;
#define ll __int128
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
int rnd(int x, int y) {
  int u = uniform_int_distribution<int>(x, y)(rng); return u;
}
ll read() { int x; cin >> x; return (ll)x; }
long long bm(long long b, long long p) {
  if(p==0) return 1 % MOD;
  long long r = bm(b, p >> 1);
  if(p&1) return (((r*r) % MOD) * b) % MOD;
  return (r*r) % MOD;
}
long long inv(long long b) { 
  return bm(b, MOD-2);
}
long long f[MAXN];
long long nCr(int n, int r) { 
  long long ans = f[n]; ans *= inv(f[r]); ans %= MOD;
  ans *= inv(f[n-r]); ans %= MOD; return ans;
}
long long fib[MAXN], lucas[MAXN];
void precomp() { 
  for(int i=0; i<MAXN; i++) f[i] = (i == 0 ? 1 % MOD : (f[i-1] * i) % MOD); 
  lucas[0] = 2;
  lucas[1] = 1;
  for(int i=2; i<MAXN; i++) lucas[i] = (lucas[i-2] + lucas[i-1]) % MOD;
  fib[0] = 0;
  fib[1] = 1;
  for(int i=2; i<MAXN; i++) fib[i] = (fib[i-2] + fib[i-1]) % MOD;
}
int fastlog(int x) {
  return (x == 0 ? -1 : 64 - __builtin_clzll(x) - 1);
}
void google(int i) { cout << "Case #" << i << ": "; }
int csb(int l, int r, int k) { // count number of [l, r] such that i & 2^k > 0
  if(l > r) return 0;
  if(l == 0) {
    int s = r / (1ll << (k+1)); // number of complete cycles
    int t = r % (1ll << (k+1));
    int ans = s * (1ll << k);
    ans += (t >= (1ll << k) ? t - (1ll << k) + 1 : 0);
    return ans;
  }
  else return csb(0, r, k) - csb(0, l - 1, k);
}
int lis(vector<int> a) {
  int n = a.size();
  int bucket[n+1];
  for(int i=1; i<=n; i++) bucket[i] = 1e18;
  int ans = 1;
  for(int x: a) {
    auto it = lower_bound(bucket + 1, bucket +n +1, x);
    int d = distance(bucket, it);
    ans = max(ans, d);
    bucket[d] = min(bucket[d], x);
  }
  return ans;
}

pair<int, int> str[4*MAXN];

void u(int l, int r, int tar, int idx, int val, int val2) {
  if(l == r) {
    str[idx] = {val, val2}; return;
  }
  int mid = (l + r) >> 1;
  if(tar <= mid) u(l, mid, tar, 2 * idx + 1, val, val2);
  else u(mid + 1, r, tar, 2 * idx + 2, val, val2);
  str[idx] = min(str[2*idx+1], str[2*idx+2]);
}

pair<int, int> qu(int l, int r, int constl, int constr, int idx) {
  if(l <= constl && constr <= r) return str[idx];
  int mid = (constl + constr) >> 1;
  if(mid < l || r < constl) return qu(l, r, mid+1, constr, 2*idx+2);
  else if(constr < l || r < mid+1) return qu(l, r, constl, mid, 2*idx+1);
  else {
    return min(qu(l, r, constl, mid, 2*idx+1), qu(l, r, mid+1, constr, 2*idx+2));
  }
}

void update(int i, int v, int w) {
  u(0, MAXN - 1, i, 0, v, w);
}
int min_idx(int l, int r) {
  pair<int, int> res = qu(l, r, 0, MAXN - 1, 0);
  if(res.first == 1e16) return -1;
  return res.second;
}

void solve(int tc) {
  int n, q;
  cin >> n >> q;
  int s[n+1], e[n+1];
  for(int i=1; i<=n; i++) cin >> s[i] >> e[i];
  set<int> sett;
  unordered_map<int, int> is;
  int nxt = 0;
  for(int i=1; i<=n; i++) {
    sett.insert(s[i]);
    sett.insert(e[i]);
  }
  for(int x: sett) {
    nxt++;
    is[x] = nxt;
  }
  for(int i=1; i<=n; i++) s[i] = is[s[i]], e[i] = is[e[i]];
  int m = nxt;
  pair<int, int> ohno1[m+1];
  for(int i=1; i<=m; i++) ohno1[i] = {1e16, 0};
  for(int i=1; i<=n; i++) ohno1[e[i]] = min(ohno1[e[i]], {s[i], i});
  for(int i=1; i<=m; i++) update(i, ohno1[i].first, ohno1[i].second);
  int st[17][n+1];
  
  for(int i=1; i<=n; i++) {
    st[0][i] = min_idx(s[i], e[i]);
    if(s[st[0][i]] == s[i]) st[0][i] = -1;
  //  cout << st[0][i] << " \n"[i == n];
  }
  for(int i=1; i<17; i++) {
    for(int j=1; j<=n; j++) {
      if(st[i-1][j] != -1) st[i][j] = st[i-1][st[i-1][j]];
      else st[i][j] = -1;
    }
  }
  while(q--) {
    int x, y;
    cin >> x >> y;
    int ans = 0;
    if(e[x] > e[y]) {
      cout << "impossible\n"; continue;
    }
    if(x == y) {
      cout << "0\n"; continue;
    }
    if(s[y] <= e[x] && e[x] <= e[y]) {
      cout << "1\n"; continue;
    }
    for(int i=16; i>=0; i--) {
      int id = st[i][y];
      if(id == -1) continue;
      if(s[id] > e[x]) {
        y = id;
        ans += (1 << i);
      }
    }
    //cout << x << " " << y << " " << ans << "\n";
    if(x == y) {
      cout << ans << "\n"; continue;
    }
    if(s[y] <= e[x] && e[x] <= e[y]) {
      cout << ans + 1 << "\n"; continue;
    }
    bool done = 0;
    for(int i=0; i<3; i++) {
      y = st[0][y];
      ans++;
      if(y == -1) {
        break;
      }
      if(s[y] <= e[x] && e[x] <= e[y]) {
        cout << ans + 1 << "\n";
        done = 1;
        break;
      }
    }
    if(!done) cout << "impossible\n";
    
  }
} 
int32_t main() {
  precomp();
  ios::sync_with_stdio(0); cin.tie(0);
  int t = 1; //cin >> t;
  for(int i=1; i<=t; i++) solve(i);
}
// I don't know geometry.
// Teaming is unfair.

/*

*/

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