| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 722543 | minhnhatnoe | Event Hopping 2 (JOI21_event2) | C++14 | 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.
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
struct node{
int left, right;
int idx;
};
vector<int> pos;
vector<node> a;
int n, k;
int test(int l, int r){
int cnt = 0;
int ptr = 0;
for (int i=0; i<a.size(); i++){
if (a[i].idx == -1) continue;
int rinter = min(a[i].right, r);
int linter = max(a[i].left, l);
if (linter < rinter) continue;
if (a[i].left < ptr) continue;
cnt++;
ptr = a[i].right;
}
return cnt;
}
void erase_inter(int l, int r){
vector<node> nxta;
for (int i=0; i<a.size(); i++){
int rinter = min(a[i].right, r);
int linter = max(a[i].left, l);
if (linter < rinter) continue;
nxta.push_back(a[i]);
}
a = move(nxta);
}
void get_input(){
cin >> n >> k;
a.resize(n);
for (int i=0; i<n; i++){
cin >> a[i].left >> a[i].right;
a[i].idx = i;
}
sort(a.begin(), a.end(), [](const node &x, const node &y){
return pair(x.left, -x.right) < pair(y.left, -y.right);
});
vector<node> nxta;
for (int i=0; i<a.size(); i++){
while (nxta.size() && nxta.back().right >= a[i].right) nxta.pop_back();
nxta.push_back(a[i]);
}
a = move(nxta);
vector<int> l(a.size());
for (int i=0; i<a.size(); i++) l[i] = a[i].left;
sort(l.begin(), l.end());
l.resize(unique(l.begin(), l.end()) - l.begin());
for (int i=0; i<a.size(); i++){
a[i].left = lower_bound(l.begin(), l.end(), a[i].left) - l.begin();
a[i].right = lower_bound(l.begin(), l.end(), a[i].right) - l.begin();
}
}
signed main(){
cin.tie(0)->sync_with_stdio(0);
get_input();
sort(a.begin(), a.end(), [](const node &x, const node &y){
return x.right < y.right;
});
if (test(-1, -1) < k){
cout << "-1\n";
return 0;
}
while (k){
pos.assign(a.size(), -1);
for (int i=0; i<a.size(); i++){
if (a[i].idx == -1) continue;
pos[a[i].idx] = i;
}
for (int i=0; i<pos.size(); i++){
if (pos[i] == -1) continue;
if (test(a[pos[i]].left, a[pos[i]].right) + 1 < k){
a[pos[i]].idx = -1;
continue;
}
a[pos[i]].idx = -1;
erase_inter(a[pos[i]].left, a[pos[i]].right);
cout << i+1 << "\n";
break;
}
k--;
}
}