Submission #1164414

#	Time	Username	Problem	Language	Result	Execution time	Memory
1164414		asli_bg	Ekoeko (COCI21_ekoeko)	C++20	0 / 110	6 ms	5568 KiB

Main

#include<bits/stdc++.h>
using namespace std;

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;

#define int long long

typedef pair<int,int> pii;
typedef vector<pii> vii;
typedef vector<int> vi;
typedef vector<bool> vb;

#define FOR(i,a) for(int i=0;i<(a);i++)
#define FORE(i,a,b) for(int i=(a);i<(b);i++)

#define all(x) x.begin(),x.end()
#define fi first
#define se second
#define pb push_back
#define sp <<" "<<

#define cont(x) for(auto el:x) cout<<el<<' ';cout<<endl;
#define contp(x) for(auto el:x) cout<<el.fi<<'-'<<el.se<<' ';cout<<endl;

#define DEBUG(x) cout<<#x sp x<<endl;
#define carp(x,y) ((x%MOD)*(y%MOD))%MOD
#define topla(x,y) ((x%MOD)+(y%MOD))%MOD
#define mid (l+r)/2

const int MAXN=1e5+5;
const int INF=1e18;

vi tut[MAXN];
int git[MAXN], val[MAXN];

int t[MAXN*4];

int n;

int query(int nd){
    int cev=0;
    while(nd>0){
        cev+=t[nd];
        nd-=nd&-nd;
    }
    return cev;
}

void update(int nd,int val){
    while(nd<=n){
        t[nd]+=val;
        nd+=nd&-nd;
    }
}

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    string s;
    cin>>n;
    cin>>s;
    int len=2*n;
    FOR(i,len){
        tut[s[i]-'a'].pb(i);
    }

    vi sol,sag;

    //first get each letter to desired half
    int bir=0;
    FOR(i,30){
        if(tut[i].empty()) continue;
        int sz=tut[i].size();
        FOR(j,sz/2){
            git[tut[i][j]]=tut[i][sz-1-j];
            sol.pb(tut[i][j]);
            sag.pb(tut[i][sz-1-j]);
        }
    }

    sort(all(sol));
    sort(all(sag));

    FOR(i,n) bir+=sol[i]-i;

    vi val(2*n,0);
    int say=1;
    FOR(i,len){
        if(val[i]!=0) continue;
        val[i]=val[git[i]]=say;
        say++;
    }

    FOR(i,sag.size()) sag[i]=val[sag[i]];

    //find inversions
    int iki=0;
    FOR(i,sag.size()){
        int el=sag[i];
        iki+=max(0LL,query(n)-query(el));
        update(el,1);
    }

    cout<<bir+iki<<endl;
}   

• Subtask 1: 0 / 10
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 20
• Subtask 5: 0 / 40