#include<bits/stdc++.h>
using namespace std;
const long long inf = (long long) 1e18 + 10;
const int inf1 = (int) 1e9 + 10;
#define int long long
#define dbl long double
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()
const int maxn = 2e5+10;
int n, q, idord[maxn], lf[maxn], rg[maxn], nx[maxn][25], pv[maxn][25];
pair<int,int> trmn[4*maxn],trmx[4*maxn];
void buildmx(int no, int l, int r) {
trmx[no] = mp(-inf,0);
if(l == r) return;
int lc=2*no,rc=2*no+1,mid=(l+r)/2;
buildmx(lc,l,mid);
buildmx(rc,mid+1,r);
}
void updmx(int no, int l, int r, int pos, pair<int,int> val) {
if(l > pos || r < pos) return;
if(l == r) {
trmx[no] = max(trmx[no],val);
return;
}
int lc=2*no,rc=2*no+1,mid=(l+r)/2;
updmx(lc,l,mid,pos,val);
updmx(rc,mid+1,r,pos,val);
trmx[no] = max(trmx[lc],trmx[rc]);
}
pair<int,int> qrymx(int no, int l, int r, int L, int R) {
if(l > R || r < L) return mp(-inf,0);
if(l >= L && r <= R) return trmx[no];
int lc=2*no,rc=2*no+1,mid=(l+r)/2;
return max(qrymx(lc,l,mid,L,R),qrymx(rc,mid+1,r,L,R));
}
void buildmn(int no, int l, int r) {
trmn[no] = mp(inf,0);
if(l == r) return;
int lc=2*no,rc=2*no+1,mid=(l+r)/2;
buildmn(lc,l,mid);
buildmn(rc,mid+1,r);
}
void updmn(int no, int l, int r, int pos, pair<int,int> val) {
if(l > pos || r < pos) return;
if(l == r) {
trmn[no] = min(trmn[no],val);
return;
}
int lc=2*no,rc=2*no+1,mid=(l+r)/2;
updmn(lc,l,mid,pos,val);
updmn(rc,mid+1,r,pos,val);
trmn[no] = min(trmn[lc],trmn[rc]);
}
pair<int,int> qrymn(int no, int l, int r, int L, int R) {
if(l > R || r < L) return mp(inf,0);
if(l >= L && r <= R) return trmn[no];
int lc=2*no,rc=2*no+1,mid=(l+r)/2;
return min(qrymn(lc,l,mid,L,R),qrymn(rc,mid+1,r,L,R));
}
void solve() {
cin >> n >> q;
vector<pair<pair<int,int>,int>> ord;
vector<int> cc;
for(int i = 1; i <= n; i++) {
int l, r; cin >> l >> r;
ord.pb(mp(mp(r,l),i));
lf[i] = l;
rg[i] = r;
cc.pb(lf[i]);
cc.pb(rg[i]);
}
sort(all(cc));
cc.erase(unique(all(cc)),cc.end());
int mxv = cc.size();
for(int i = 1; i <= n; i++) {
lf[i] = upper_bound(all(cc),lf[i])-cc.begin();
rg[i] = upper_bound(all(cc),rg[i])-cc.begin();
}
// sort(all(ord));
buildmx(1,1,mxv);
for(int i = 1; i <= n; i++) {
updmx(1,1,mxv,lf[i],mp(rg[i],i));
}
for(int i = 1; i <= n; i++) {
nx[i][0] = 0;
// for(int j = 1; j <= n; j++) {
// if(lf[j] <= rg[i] && rg[j] > rg[i]) {
// if(nx[i][0] == 0 || rg[j] > rg[nx[i][0]]) nx[i][0] = j;
// }
// }
auto valnx = qrymx(1,1,mxv,1,rg[i]);
if(valnx.fr == rg[i]) nx[i][0] = 0;
else nx[i][0] = valnx.sc;
pv[i][0] = 0;
for(int j = 1; j <= n; j++) {
if(j == i || !(lf[i] <= rg[j] && rg[j] <= rg[i]) || !(lf[j] < lf[i])) continue;
if(pv[i][0] == 0 || lf[j] < lf[pv[i][0]]) pv[i][0] = j;
}
// cout << i << " " << nx[i][0] << " " << pv[i][0] << endl;
}
for(int j = 1; j <= 20; j++) {
for(int i = 1; i <= n; i++) {
nx[i][j] = nx[nx[i][j-1]][j-1];
pv[i][j] = pv[pv[i][j-1]][j-1];
}
}
while(q--) {
int s,e; cin >> s >> e;
int ans = 0;
for(int j = 20; j >= 0; j--) {
if(nx[s][j] != 0 && rg[nx[s][j]] < rg[e]) {
ans+= (1<<j);
s = nx[s][j];
}
}
for(int j = 20; j >= 0; j--) {
if(pv[e][j] != 0 && lf[pv[e][j]] > lf[s]) {
ans+= (1<<j);
e = pv[e][j];
}
}
if(s == e) {
cout << ans << endl;
}
else if(lf[e] <= rg[s] && rg[s] <= rg[e]) {
cout << ans+1 << endl;
}
else if(nx[s][0] != 0 && lf[e] <= rg[nx[s][0]] && rg[nx[s][0]] <= rg[e]) {
cout << ans+2 << endl;
}
else if(pv[e][0] != 0 && lf[pv[e][0]] <= rg[s] && rg[s] <= rg[pv[e][0]]) {
cout << ans+2 << endl;
}
else {
cout << "impossible" << endl;
}
}
}
int32_t main() {
ios::sync_with_stdio(false); cin.tie(0);
freopen("in.in", "r", stdin);
// freopen("out.out", "w", stdout);
int tt = 1;
// cin >> tt;
while(tt--) {
solve();
}
}
Compilation message
events.cpp: In function 'int32_t main()':
events.cpp:160:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
160 | freopen("in.in", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
6 ms |
724 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
4 ms |
724 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
4 ms |
724 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
4 ms |
724 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
4 ms |
748 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
6 ms |
724 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
