Submission #799923

#	Time	Username	Problem	Language	Result	Execution time	Memory
799923		cig32	Mountains (NOI20_mountains)	C++17	100 / 100	722 ms	27080 KiB

Mountains

#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/detail/standard_policies.hpp>
using namespace __gnu_pbds;
#define int long long
typedef tree<pair<int,int>, null_type, less<pair<int,int> >, rb_tree_tag, tree_order_statistics_node_update> ost;
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n;
  cin >> n;
  int a[n+1];
  for(int i=1; i<=n; i++) cin >> a[i];
  ost left, right;
  for(int i=3; i<=n; i++) right.insert({a[i],i});
  left.insert({a[1],1});
  int ans = left.order_of_key({a[2],0}) * right.order_of_key({a[2],0});
  for(int i=3; i<n; i++) {
    left.insert({a[i-1],i-1});
    right.erase({a[i],i});
    ans += left.order_of_key({a[i],0}) * right.order_of_key({a[i],0});
  }
  cout << ans << "\n";
}

• Subtask 1: 2 / 2
• Subtask 2: 4 / 4
• Subtask 3: 9 / 9
• Subtask 4: 36 / 36
• Subtask 5: 28 / 28
• Subtask 6: 9 / 9
• Subtask 7: 12 / 12