Submission #521476

#	Time	Username	Problem	Language	Result	Execution time	Memory
521476		errorgorn	Ekoeko (COCI21_ekoeko)	C++17	110 / 110	17 ms	3440 KiB

Main

// Super Idol的笑容
//    都没你的甜
//  八月正午的阳光
//    都没你耀眼
//  热爱105°C的你
// 滴滴清纯的蒸馏水

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << ": " << x << endl

#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define lb lower_bound
#define ub upper_bound

#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()

#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
//change less to less_equal for non distinct pbds, but erase will bug

mt19937 rng(chrono::system_clock::now().time_since_epoch().count());

int fen[100005];

void upd(int i,int j){
	while (i<100005){
		fen[i]+=j;
		i+=i&-i;
	}
}

int query(int i){
	int res=0;
	while (i){
		res+=fen[i];
		i-=i&-i;
	}
	return res;
}

int n;
string s;

vector<int> v[26];
bool pos[200005];

vector<int> p1[26];
vector<int> p2[26];

int arr[100005];

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin.exceptions(ios::badbit | ios::failbit);
	
	cin>>n;
	cin>>s;
	
	rep(x,0,2*n){
		v[s[x]-'a'].pub(x);
	}
	
	rep(x,0,26){
		rep(y,0,sz(v[x])/2) pos[v[x][y]]=true;
	}
	
	ll ans=0;
	ll curr=0;
	
	//rep(x,0,2*n) cout<<pos[x]<<" "; cout<<endl;
	
	rep(x,0,2*n){
		if (!pos[x]) curr++;
		else ans+=curr;
	}
	
	int i1=0,i2=0;
	
	rep(x,0,2*n){
		if (!pos[x]) p1[s[x]-'a'].pub(i1++);
		else p2[s[x]-'a'].pub(i2++);
	}
	
	rep(x,0,26){
		rep(y,0,sz(p1[x])) arr[p1[x][y]]=p2[x][y];
	}
	
	rep(x,2,n+1) upd(x,1);
	
	rep(x,0,n){
		ans+=query(arr[x]+1)-x;
		upd(1,1);
		upd(arr[x]+1,-1);
	}
	
	cout<<ans<<endl;
}

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 20 / 20
• Subtask 5: 40 / 40