Submission #593449

#	Time	Username	Problem	Language	Result	Execution time	Memory
593449		slime	Event Hopping (BOI22_events)	C++14	30 / 100	481 ms	83592 KiB

events

#include "bits/stdc++.h"
using namespace std;
#define int long long
#ifdef ONLINE_JUDGE
const int MAXN = 3e5 + 10;
#endif
#ifndef ONLINE_JUDGE
const int MAXN = 1029;
#endif
const int MOD = 1e9 + 7;
#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 gay(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;
}
struct event {
  int s, e;
  int id;
};
bool cmp_s(event x, event y) {
  return x.s < y.s;
}
bool cmp_e(event x, event y) {
  return x.e < y.e;
}
struct segtree_basic {
  struct node {
    int lazyval, mi, ma, sum; char lazytag;
    int len; // not changing
  };
  int stok;
  vector<node> st;
  void bu(int l, int r, int idx) {
    st[idx].lazyval = st[idx].mi = st[idx].ma = st[idx].sum = 0;
    st[idx].lazytag = '?';
    st[idx].len = r - l + 1;
    if(l == r) {
      return;
    }
    int mid = (l + r) >> 1;
    bu(l, mid, 2*idx+1);
    bu(mid+1, r, 2*idx+2);
  }
  void push_down(int idx) {
    if(st[idx].lazytag == '?') return;
    if(st[idx].lazytag == ':') {
      st[2*idx+1].lazyval = st[idx].lazyval;
      st[2*idx+1].mi = st[idx].lazyval;
      st[2*idx+1].ma = st[idx].lazyval;
      st[2*idx+1].sum = st[idx].lazyval * st[2*idx+1].len;
      st[2*idx+1].lazytag = ':';
 
      st[2*idx+2].lazyval = st[idx].lazyval;
      st[2*idx+2].mi = st[idx].lazyval;
      st[2*idx+2].ma = st[idx].lazyval;
      st[2*idx+2].sum = st[idx].lazyval * st[2*idx+2].len;
      st[2*idx+2].lazytag = ':';
 
    }
    else {
      st[2*idx+1].lazyval += st[idx].lazyval;
      st[2*idx+1].mi += st[idx].lazyval;
      st[2*idx+1].ma += st[idx].lazyval;
      st[2*idx+1].sum += st[idx].lazyval * st[2*idx+1].len;
      st[2*idx+1].lazytag = (st[2*idx+1].lazytag == ':' ? ':' : '+');
 
      st[2*idx+2].lazyval += st[idx].lazyval;
      st[2*idx+2].mi += st[idx].lazyval;
      st[2*idx+2].ma += st[idx].lazyval;
      st[2*idx+2].sum += st[idx].lazyval * st[2*idx+2].len;
      st[2*idx+2].lazytag = (st[2*idx+2].lazytag == ':' ? ':' : '+');
    }
    st[idx].lazytag = '?';
    st[idx].lazyval = 0;
  }
  void push_up(int idx) {
    st[idx].mi = min(st[2*idx+1].mi, st[2*idx+2].mi);
    st[idx].ma = max(st[2*idx+1].ma, st[2*idx+2].ma);
    st[idx].sum = st[2*idx+1].sum + st[2*idx+2].sum;
  }
  void u1(int l, int r, int constl, int constr, int idx, int val) { // range := v
    if(l <= constl && constr <= r) {
      st[idx].lazyval = val;
      st[idx].mi = val;
      st[idx].ma = val;
      st[idx].sum = val * st[idx].len;
      st[idx].lazytag = ':';
      return;
    }
    int mid = (constl + constr) >> 1;
    push_down(idx);
    if(mid < l || r < constl) u1(l, r, mid+1, constr, 2*idx+2, val);
    else if(constr < l || r < mid + 1) u1(l, r, constl, mid, 2*idx+1, val);
    else {
      u1(l, r, constl, mid, 2*idx+1, val);
      u1(l, r, mid+1, constr, 2*idx+2, val);
    }
    push_up(idx);
  }
 
  void u2(int l, int r, int constl, int constr, int idx, int val) { // range += v
    if(l <= constl && constr <= r) {
      st[idx].lazyval += val;
      st[idx].mi += val;
      st[idx].ma += val;
      st[idx].sum += val * st[idx].len;
      st[idx].lazytag = (st[idx].lazytag == ':' ? ':' : '+');
      return;
    }
    int mid = (constl + constr) >> 1;
    push_down(idx);
    if(mid < l || r < constl) u2(l, r, mid+1, constr, 2*idx+2, val);
    else if(constr < l || r < mid + 1) u2(l, r, constl, mid, 2*idx+1, val);
    else {
      u2(l, r, constl, mid, 2*idx+1, val);
      u2(l, r, mid+1, constr, 2*idx+2, val);
    }
    push_up(idx);
  }
 
  int qu1(int l, int r, int constl, int constr, int idx) { // range min
    if(l <= constl && constr <= r) return st[idx].mi;
    int mid = (constl + constr) >> 1;
    push_down(idx);
    if(mid < l || r < constl) return qu1(l, r, mid+1, constr, 2*idx+2);
    else if(constr < l || r < mid + 1) return qu1(l, r, constl, mid, 2*idx+1);
    else {
      return min(qu1(l, r, constl, mid, 2*idx+1), qu1(l, r, mid+1, constr, 2*idx+2));
    }
  }
 
  int qu2(int l, int r, int constl, int constr, int idx) { // range max
    if(l <= constl && constr <= r) return st[idx].ma;
    int mid = (constl + constr) >> 1;
    push_down(idx);
    if(mid < l || r < constl) return qu2(l, r, mid+1, constr, 2*idx+2); 
    else if(constr < l || r < mid + 1) return qu2(l, r, constl, mid, 2*idx+1);
    else {
      return max(qu2(l, r, constl, mid, 2*idx+1), qu2(l, r, mid+1, constr, 2*idx+2));
    }
  }
  int qu3(int l, int r, int constl, int constr, int idx) { // range sum
    if(l <= constl && constr <= r) return st[idx].sum;
    int mid = (constl + constr) >> 1;
    push_down(idx);
    if(mid < l || r < constl) return qu3(l, r, mid+1, constr, 2*idx+2);
    else if(constr < l || r < mid + 1) return qu3(l, r, constl, mid, 2*idx+1);
    else {
      return qu3(l, r, constl, mid, 2*idx+1) + qu3(l, r, mid+1, constr, 2*idx+2);
    }
  }
  int qu4(int l, int r, int constl, int constr, int idx, int val) { // first at least v
    if(l <= constl && constr <= r) {
      if(st[idx].ma < val) return -1;
      while(constl < constr) {
        int mid = (constl + constr) >> 1;
        push_down(idx);
        if(st[2*idx+1].ma >= val) constr = mid, idx = 2*idx + 1;
        else constl = mid+1, idx = 2*idx + 2;
      }
      return constl;
    }
    int mid = (constl + constr) >> 1;
    push_down(idx);
    if(mid < l || r < constl) return qu4(l, r, mid+1, constr, 2*idx+2, val);
    else if(constr < l || r < mid + 1) return qu4(l, r, constl, mid, 2*idx+1, val);
    else {
      int lchild = qu4(l, r, constl, mid, 2*idx+1, val);
      if(lchild != -1) return lchild;
      return qu4(l, r, mid+1, constr, 2*idx+2, val);
    }
  }
  int qu5(int l, int r, int constl, int constr, int idx, int val) { // first at most v
    if(l <= constl && constr <= r) {
      if(st[idx].mi > val) return -1;
      while(constl < constr) {
        int mid = (constl + constr) >> 1;
        push_down(idx);
        if(st[2*idx+1].mi <= val) constr = mid, idx = 2*idx + 1;
        else constl = mid+1, idx = 2*idx + 2;
      }
      return constl;
    }
    int mid = (constl + constr) >> 1;
    push_down(idx);
    if(mid < l || r < constl) return qu5(l, r, mid+1, constr, 2*idx+2, val);
    else if(constr < l || r < mid + 1) return qu5(l, r, constl, mid, 2*idx+1, val);
    else {
      int lchild = qu5(l, r, constl, mid, 2*idx+1, val);
      if(lchild != -1) return lchild;
      return qu5(l, r, mid+1, constr, 2*idx+2, val);
    }
  }
  int qu6(int l, int r, int constl, int constr, int idx, int val) { // last at least v
    if(l <= constl && constr <= r) {
      if(st[idx].ma < val) return -1;
      while(constl < constr) {
        int mid = (constl + constr) >> 1;
        push_down(idx);
        if(st[2*idx+2].ma >= val) constl = mid+1, idx = 2*idx + 2;
        else constr = mid, idx = 2*idx + 1;
      }
      return constl;
    }
    int mid = (constl + constr) >> 1;
    push_down(idx);
    if(mid < l || r < constl) return qu6(l, r, mid+1, constr, 2*idx+2, val);
    else if(constr < l || r < mid + 1) return qu6(l, r, constl, mid, 2*idx+1, val);
    else {
      int rchild = qu6(l, r, mid+1, constr, 2*idx+2, val);
      if(rchild != -1) return rchild;
      return qu6(l, r, constl, mid, 2*idx+1, val);
    }
  }
  int qu7(int l, int r, int constl, int constr, int idx, int val) { // last at most v
    if(l <= constl && constr <= r) {
      if(st[idx].mi > val) return -1;
      while(constl < constr) {
        int mid = (constl + constr) >> 1;
        push_down(idx);
        if(st[2*idx+2].mi <= val) constl = mid+1, idx = 2*idx + 2;
        else constr = mid, idx = 2*idx + 1;
      }
      return constl;
    }
    int mid = (constl + constr) >> 1;
    push_down(idx);
    if(mid < l || r < constl) return qu7(l, r, mid+1, constr, 2*idx+2, val);
    else if(constr < l || r < mid + 1) return qu7(l, r, constl, mid, 2*idx+1, val);
    else {
      int rchild = qu7(l, r, mid+1, constr, 2*idx+2, val);
      if(rchild != -1) return rchild;
      return qu7(l, r, constl, mid, 2*idx+1, val);
    }
  }
  public:
  void resize(int k) {
    st.resize(4*k + 10);
    stok = k;
    bu(0, k, 0);
  }
  void range_assign(int l, int r, int v) { u1(l, r, 0, stok, 0, v); }
 
  void range_add(int l, int r, int v) { u2(l, r, 0, stok, 0, v); }
 
  int query_min(int l, int r) { return qu1(l, r, 0, stok, 0); }
 
  int query_max(int l, int r) { return qu2(l, r, 0, stok, 0); }
 
  int query_sum(int l, int r) { return qu3(l, r, 0, stok, 0); }
 
  int query_firstAtLeast(int l, int r, int v) { return qu4(l, r, 0, stok, 0, v); }
 
  int query_firstAtMost(int l, int r, int v) { return qu5(l, r, 0, stok, 0, v); }
 
  int query_lastAtLeast(int l, int r, int v) { return qu6(l, r, 0, stok, 0, v); } 
 
  int query_lastAtMost(int l, int r, int v) { return qu7(l, r, 0, stok, 0, v); }
};
bool normal_order(event x, event y) {
  return x.id < y.id;
}
void solve(int tc) {
  int n, q;
  cin >> n >> q;
  event a[n+1], b[n+1];
  set<int> discrete;
  for(int i=1; i<=n; i++) {
    cin >> a[i].s >> a[i].e;
    discrete.insert(a[i].s);
    discrete.insert(a[i].e);
    a[i].id = i;
    b[i].s = a[i].s;
    b[i].e = a[i].e;
    b[i].id = a[i].id;
  }
  int owo = 0;
  map<int, int > is;
  for(int x: discrete) {
    owo++;
    is[x] = owo;
  }
  for(int i=1; i<=n; i++) {
    a[i].s = is[a[i].s];
    b[i].s = is[b[i].s];
    a[i].e = is[a[i].e];
    b[i].e = is[b[i].e];
  }
  int opt[n+1];
  for(int i=1; i<=n; i++) opt[i] = -1;
  sort(a+1, a+n+1, cmp_s);
  sort(b+1, b+n+1, cmp_e);
  int j = 0;
  segtree_basic stb;
  stb.resize(2*n);
  for(int i=1; i<=n; i++) {
    while(j+1 <= n && a[j+1].s <= b[i].e) {
      j++;
      stb.range_assign(a[j].e, a[j].e, a[j].id);
    }
    int idx = stb.query_lastAtLeast(b[i].e, 2*n, 1);
    if(idx != -1) {
      idx = stb.query_min(idx, idx);
      opt[b[i].id] = idx;
    }
  }
  for(int i=1; i<=n; i++) if(opt[i] != -1 && b[opt[i]].e == b[i].e) opt[i] = -1;
  int st[17][n+1];
  for(int i=1; i<=n; i++) st[0][i] = opt[i];
  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;
    }
  }
  sort(b+1, b+n+1, normal_order);
  int mi[2*n + 1]; // for all events that end at i, min strat time
  for(int i=1; i<=2*n; i++) mi[i] = 1e9;
  for(int i=1; i<=n; i++) mi[b[i].e] = min(mi[b[i].e], b[i].s);
  while(q--) {
    int fi, se;
    cin >> fi >> se;
    if(fi == se) {
      cout << "0\n"; continue;
    }
    int ans = 0;
    for(int j=16; j>=0; j--) {
      if(st[j][fi] != -1 && b[st[j][fi]].e < b[se].e) {
        fi = st[j][fi];
        ans += (1<<j);
      }
    }
    if(b[se].s <= b[fi].e && b[fi].e <= b[se].e) cout << ans + 1 << "\n";
    else if(mi[b[se].e] <= b[fi].e && b[fi].e <= b[se].e) cout << ans + 2 << "\n";
    else 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.

/*
6 1

4 7
11 12
7 8
2 7
10 12
6 10


5 3
*/

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