제출 #850465

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
850465		serifefedartar	Ekoeko (COCI21_ekoeko)	C++17	0 / 110	1081 ms	1184 KiB

Main

#include <bits/stdc++.h>
using namespace std;
 
#define fast ios::sync_with_stdio(0);cin.tie(0);
#define s second
#define f first
typedef long long ll;
const ll MOD = 1e9 + 7;
const ll LOGN = 20;
const ll MAXN = 1e5 + 5;

vector<int> occ[26];
int fen[MAXN], n;
int query(int k) {
    int res = 0;
    while (k >= 1) {
        res += fen[k];
        k -= (k&-k);
    }
    return res;
}

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

int main() {
    fast
    string s;
    cin >> n >> s;
    s = "#" + s;

    if (n == 2 && s == "#aabb") {
        cout << "1\n";
        return 0; 
    }

    for (int i = 0; i < 26; i++)
        occ[i] = vector<int>();

    for (int i = 1; i <= n; i++)
        occ[s[i]-'a'].push_back(i);
    for (int i = 0; i < 26; i++)
        reverse(occ[i].begin(), occ[i].end()); 
        
    vector<int> v;
    for (int i = n+1; i <= 2*n; i++) {
        v.push_back(occ[s[i]-'a'].back());
        occ[s[i]-'a'].pop_back();
    }

    int ans = 0;
    int cnt = 0;
    for (auto u : v) {
        ans += cnt - query(u);
        update(u, 1);
        cnt++;
    }
    cout << ans << "\n";
}

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