#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10;
struct interval
{
int s, e, idx;
}seg[maxn];
int n, q;
pair < int, int > task[maxn];
void input()
{
cin >> n >> q;
for (int i = 1; i <= n; i ++)
{
cin >> seg[i].s >> seg[i].e;
seg[i].idx = i;
}
for (int i = 1; i <= q; i ++)
{
cin >> task[i].first >> task[i].second;
}
}
bool cmp_end(interval seg1, interval seg2)
{
return seg1.e < seg2.e;
}
int lf[maxn], rev[maxn];
void build_graph()
{
sort(seg + 1, seg + n + 1, cmp_end);
for (int i = 1; i <= n; i ++)
{
rev[seg[i].idx] = i;
}
for (int i = 1; i <= n; i ++)
{
lf[i] = 1;
while(seg[lf[i]].e < seg[i].s)
lf[i] ++;
}
}
void answer_queries()
{
/**cout << "----------------------" << endl;
for (int i = 1; i <= n; i ++)
cout << seg[i].s << " :: " << seg[i].e << endl;*/
for (int i = 1; i <= q; i ++)
{
int st = rev[task[i].first], en = rev[task[i].second];
if (st > en)
{
cout << "impossible" << endl;
continue;
}
int steps = 0, last = en + 1, bound = en;
bool done = false;
while(bound > st)
{
///cout << last << " " << bound << endl;
steps ++;
int new_bound = bound;
for (int i = bound; i < last; i ++)
new_bound = min(new_bound, lf[i]);
///cout << new_bound << endl;
if (new_bound == bound)
{
done = true;
break;
}
last = bound;
bound = new_bound;
}
if (done)
cout << "impossible" << endl;
else
cout << steps << endl;
}
}
void solve()
{
input();
build_graph();
answer_queries();
}
int main()
{
speed();
solve();
return 0;
}
Compilation message
events.cpp: In function 'int main()':
events.cpp:102:5: error: 'speed' was not declared in this scope
102 | speed();
| ^~~~~
