# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1120246 | vjudge1 | Event Hopping (BOI22_events) | C11 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
// Bolatulu
#include <bits/stdc++.h>
// #include <art.h>
/*
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
*/
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
#define pb push_back
#define eb emplace_back
#define ins insert
#define F first
#define S second
#define md (tl+tr)/2
#define TL v+v,tl,md
#define TR v+v+1,md+1,tr
#define Tl t[v].l,tl,md
#define Tr t[v].r,md+1,tr
#define all(x) (x).begin(),(x).end()
#define yes cout << "YES\n"
#define no cout << "NO\n"
#define int long long
#define file(s) freopen(s".in", "r", stdin); freopen(s".out", "w", stdout);
#define ld long double
using namespace std;
int binpow(int a,int n,int M) {
if (n==0)
return 1;
if (n%2!=0)
return (a * binpow(a,n-1,M))%M;
int z=binpow(a,n/2,M);
return (z*z)%M;
}
const ll INF = 1e18+7;
const int N = 1e5+7;
const int M = 1e4+7;
const ld eps = 1e-3;
int n,q,s[N],e[N],dp[N],pos[N],ans[N];
vector <pair <int,int>> f[N];
void solve() {
cin >> n >> q;
vector <pair <pair <int,int>,int>> v;
for (int i=1;i<=n;i++) {
cin >> s[i] >> e[i];
v.pb({{e[i],s[i]},i});
}
sort(all(v));
for (int i=1;i<=n;i++) {
s[i]=v[i-1].F.S, e[i]=v[i-1].F.F;
pos[v[i-1].S]=i;
// pos[i]=v[i-1].S;
}
for (int i=1;i<=q;i++) {
int l,r;
cin >> l >> r;
l=pos[l], r=pos[r];
f[l].eb(r,i);
}
for (int i=1;i<=n;i++) {
if (f[i].empty())
continue;
// cout << s[i] << ' ' << e[i] << ' ' << pos[i] << '\n';
vector <pair <int,int>> d;
dp[i]=0;
d.eb(e[i],0);
int R=0;
for (auto now : f[i])
R=max(R,now.F);
for (int j=i+1;j<=R;j++) {
int l=-1,r=d.size();
while (l+1<r) {
int mid=(l+r)/2;
if (d[mid].F>=s[j])
r=mid;
else
l=mid;
}
if (r==d.size())
dp[j]=n+1;
else
dp[j]=d[r].S+1;
while (!d.empty() and d.back().S>=dp[j])
d.pop_back();
d.eb(e[j],dp[j]);
}
for (auto now : f[i]) {
if (now.F<i or dp[now.F]>n)
ans[now.S]=-1;
else
ans[now.S]=dp[now.F];
}
}
for (int i=1;i<=q;i++) {
if (ans[i]==-1)
cout << "impossible\n";
else
cout << ans[i] << '\n';
}
}
signed main() {
//file("jenga");
ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
int test = 1;
// cin >> test;
while (test--) {
solve();
if (test)
cout << '\n';
}
return 0;
}