#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define ll long long
#define pb push_back
const int nax=3e5+5;
vector<pair<int,int>> segtree(4*nax);
struct query{
int x,type,idx,value;
};
bool compare(query a,query b){
if(a.x!=b.x) return a.x<b.x;
else if(a.type!=b.type) return a.type<b.type;
else return a.idx<b.idx;
}
vector<query> sweep;
void build(int pos,int l,int r){
if(l==r){
segtree[pos]={sweep[l].value,sweep[l].idx};
return;
}
int mid=(r+l)/2;
build(pos*2+1,l,mid);
build(pos*2+2,mid+1,r);
segtree[pos]=max(segtree[pos*2+1],segtree[pos*2+2]);
return;
}
pair<int,int> query(int pos,int l,int r,int left,int right){
if(l>r||l>right||r<left) return {-1,-1};
else if(l>=left&&r<=right) return segtree[pos];
int mid=(r+l)/2;
return max(query(pos*2+1,l,mid,left,right),query(pos*2+2,mid+1,r,left,right));
}
int main(){
int n,q;
cin>>n>>q;
vector<pair<int,int>> tab(n);
for (int i = 0; i < n; ++i)
{
cin>>tab[i].fi>>tab[i].se;
sweep.pb({tab[i].fi,0,i,tab[i].se});
sweep.pb({tab[i].se,1,i,tab[i].se});
}
sort(sweep.begin(),sweep.end(),compare);
pair<int,int> pos[n];
for (int i = 0; i < sweep.size(); ++i)
{
if(sweep[i].type==0){
pos[sweep[i].idx].fi=i;
}else{
pos[sweep[i].idx].se=i;
}
}
build(0,0,sweep.size()-1);
int dp[n][20];
int dp1[n][20];
for (int i = 0; i < sweep.size(); ++i)
{
if(sweep[i].type==1){
dp[sweep[i].idx][0]=query(0,0,sweep.size()-1,0,pos[sweep[i].idx].se).se;
dp1[sweep[i].idx][0]=query(0,0,sweep.size()-1,pos[sweep[i].idx].fi,pos[sweep[i].idx].se).se;
}
}
for (int j = 1; j < 20; ++j)
{
for (int i = 0; i < n; ++i)
{
dp[i][j]=dp[dp[i][j-1]][j-1];
dp1[i][j]=dp1[dp[i][j-1]][j-1];
}
}
while(q--){
int s,e;
cin>>s>>e;
s--;
e--;
int ans=0;
if(s==e){
cout <<0<<endl;
continue;
}else if(tab[s].fi==tab[e].fi&&tab[s].se==tab[e].se){
cout <<1<<endl;
continue;
}else if(tab[e].se<=tab[s].fi&&tab[e].fi<tab[s].fi){
cout <<"impossible"<<endl;
continue;
}else if(tab[e].fi<=tab[s].fi&&tab[s].fi<=tab[e].se&&tab[e].se<=tab[s].se){
cout <<"impossible"<<endl;
continue;
}
for (int i = 19; i >= 0; --i)
{
if(tab[dp[s][i]].se<tab[e].fi){
ans+=(1<<i);
s=dp[s][i];
}
}
//cout <<"nab "<<s<<" "<<ans<<endl;
for (int i = 19; i >= 0; --i)
{
if(tab[dp1[s][i]].se<tab[e].fi){
ans+=(1<<i);
s=dp[s][i];
}
}
if(tab[dp1[s][0]].se<tab[e].fi) cout <<"impossible"<<endl;
else if(tab[dp1[s][0]].se>tab[e].se) cout <<"impossible"<<endl;
else if(tab[s].se<tab[e].fi) cout <<ans+2<<endl;
else cout <<ans+1<<endl;
}
}
Compilation message
events.cpp: In function 'int main()':
events.cpp:47:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<query>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
47 | for (int i = 0; i < sweep.size(); ++i)
| ~~^~~~~~~~~~~~~~
events.cpp:58:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<query>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
58 | for (int i = 0; i < sweep.size(); ++i)
| ~~^~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
9820 KB |
Output is correct |
2 |
Correct |
286 ms |
30840 KB |
Output is correct |
3 |
Correct |
281 ms |
30752 KB |
Output is correct |
4 |
Correct |
313 ms |
31416 KB |
Output is correct |
5 |
Correct |
288 ms |
30908 KB |
Output is correct |
6 |
Correct |
288 ms |
33932 KB |
Output is correct |
7 |
Correct |
295 ms |
34744 KB |
Output is correct |
8 |
Correct |
306 ms |
34748 KB |
Output is correct |
9 |
Correct |
285 ms |
35036 KB |
Output is correct |
10 |
Correct |
293 ms |
34316 KB |
Output is correct |
11 |
Incorrect |
333 ms |
34912 KB |
Output isn't correct |
12 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
9820 KB |
Output is correct |
2 |
Correct |
3 ms |
9820 KB |
Output is correct |
3 |
Correct |
3 ms |
9820 KB |
Output is correct |
4 |
Correct |
4 ms |
10076 KB |
Output is correct |
5 |
Incorrect |
3 ms |
9816 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
9820 KB |
Output is correct |
2 |
Correct |
3 ms |
9820 KB |
Output is correct |
3 |
Correct |
3 ms |
9820 KB |
Output is correct |
4 |
Correct |
4 ms |
10076 KB |
Output is correct |
5 |
Incorrect |
3 ms |
9816 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
9820 KB |
Output is correct |
2 |
Correct |
3 ms |
9820 KB |
Output is correct |
3 |
Correct |
3 ms |
9820 KB |
Output is correct |
4 |
Correct |
4 ms |
10076 KB |
Output is correct |
5 |
Incorrect |
3 ms |
9816 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
281 ms |
30656 KB |
Output is correct |
2 |
Correct |
300 ms |
30800 KB |
Output is correct |
3 |
Correct |
325 ms |
30656 KB |
Output is correct |
4 |
Correct |
281 ms |
31412 KB |
Output is correct |
5 |
Correct |
303 ms |
31164 KB |
Output is correct |
6 |
Incorrect |
322 ms |
31048 KB |
Output isn't correct |
7 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
9820 KB |
Output is correct |
2 |
Correct |
286 ms |
30840 KB |
Output is correct |
3 |
Correct |
281 ms |
30752 KB |
Output is correct |
4 |
Correct |
313 ms |
31416 KB |
Output is correct |
5 |
Correct |
288 ms |
30908 KB |
Output is correct |
6 |
Correct |
288 ms |
33932 KB |
Output is correct |
7 |
Correct |
295 ms |
34744 KB |
Output is correct |
8 |
Correct |
306 ms |
34748 KB |
Output is correct |
9 |
Correct |
285 ms |
35036 KB |
Output is correct |
10 |
Correct |
293 ms |
34316 KB |
Output is correct |
11 |
Incorrect |
333 ms |
34912 KB |
Output isn't correct |
12 |
Halted |
0 ms |
0 KB |
- |