Submission #642806

#	Time	Username	Problem	Language	Result	Execution time	Memory
642806		Codula	Mountains (NOI20_mountains)	C++17	100 / 100	901 ms	88296 KiB

Mountains

//IOI 2023 I am coming.
 
#include "bits/stdc++.h"
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
 
using namespace std;
using namespace __gnu_pbds;
 
#define fast ios_base::sync_with_stdio(false);cin.tie(nullptr)
#define int int64_t
#define pb push_back
#define deb(x) cerr<<"("<<#x<<"="<<x<<','<<__LINE__<<")"<<endl; 
#define ordered_set tree<pair<int,int>, null_type,less<pair<int,int>>, rb_tree_tag,tree_order_statistics_node_update>
 
int32_t main(){
	fast;
	int n;
	cin>>n;
	vector<int>a(n);
	for(int i=0;i<n;++i){
		cin>>a[i];
	}
	ordered_set o1,o2;
	//~ map<int,int>mp;
	vector<int>pref(3e5+1),pref2(3e5+1);
	map<int,int>mp,mp2;
	for(int i=0;i<n;++i){
		int dx=o1.order_of_key({a[i],i})-mp[a[i]];
		pref[i]=dx;
		o1.insert({a[i],i});
		mp[a[i]]+=1;
	}
	//~ map<int,int>mp2;
	for(int i=n-1;i>=0;--i){
		int dx=o2.order_of_key({a[i],-i})-mp2[a[i]];
		pref2[i]=dx;
		o2.insert({a[i],-i});
		mp2[a[i]]+=1;
	}
	int ans=0;
	for(int i=0;i<n;++i){
		//~ deb(pref[i]);
		//~ deb(pref2[i]);
		ans+=(pref[i]*pref2[i]);
	}
	cout<<ans<<"\n";
    return 0;
}

• 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