#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], rf[maxn];
map < int, int > fix;
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] ++;
if (fix[seg[i].e] == 0)
fix[seg[i].e] = lf[i];
else
fix[seg[i].e] = min(fix[seg[i].e], 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 (seg[st].e == seg[en].e && st != en)
{
cout << 1 << endl;
continue;
}
if (st > en)
{
cout <<< "impossible" << endl;
continue;
}
int steps = 0, last_left = en + 1;
int bound_left = en;
bool done = false;
while(!(st >= bound_left))
{
///cout << last_left << " " << bound_left << endl;
steps ++;
int new_left = bound_left;
for (int i = bound_left; i < last_left; i ++)
{
new_left = min(new_left, lf[i]);
}
///cout << "here " << lf[en] << " " << fix[seg[en].e] << " " << seg[en].s << endl;
//if (steps == 2)
//new_left = min(new_left, fix[seg[en].e]);
///cout << new_bound << endl;
if (new_left == bound_left)
{
done = true;
break;
}
last_left = bound_left;
bound_left = new_left;
}
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 'void answer_queries()':
events.cpp:78:20: error: expected primary-expression before '<' token
78 | cout <<< "impossible" << endl;
| ^
events.cpp:78:35: error: invalid operands of types 'const char [11]' and '<unresolved overloaded function type>' to binary 'operator<<'
78 | cout <<< "impossible" << endl;
| ~~~~~~~~~~~~~^~~~~~~
