Submission #815743

#	Time	Username	Problem	Language	Result	Execution time	Memory
815743		hohoho	Ekoeko (COCI21_ekoeko)	C++14	110 / 110	59 ms	7500 KiB

Main

#include <bits/stdc++.h>
 
using namespace std;
 
const int N = (1e5 + 5) * 2;
 
int n, cnt[26];
long long ans;
 
string str;
 
vector<char> strv;
 
vector<int> indx[26], v;
 
void up(int* Tree, int index, int s, int e, int num)
{
   
    if (s == num and e == num) {
        Tree[index] = 1;
        return;
    }
 
    if (num < s or num > e) {
        return;
    }
 
    int mid = (s + e) >> 1;
    up(Tree, 2 * index, s, mid, num);
    up(Tree, 2 * index + 1, mid + 1, e, num);
 
    Tree[index] = Tree[2 * index] + Tree[2 * index + 1];
}
 
int query(int* Tree, int index, int s,
          int e, int qs, int qe)
{
    
    if (qs <= s and e <= qe) {
        return Tree[index];
    }
 
    
    if (s > qe or e < qs) {
        return 0;
    }
 
    int mid = (s + e) >> 1;
 
    return query(Tree, 2 * index, s,
                 mid, qs, qe)
           + query(Tree, 2 * index + 1,
                   mid + 1, e, qs, qe);
}
 
int main(){
    ios_base::sync_with_stdio(false);cin.tie(NULL);
 
    cin >> n;
    cin >> str;
 
    n *= 2;
 
    for(auto c : str) cnt[c - 'a']++;
 
    for(int i = 0; i < n; i++){
        if(cnt[str[i] - 'a'] > 0){
            strv.push_back(str[i]);
            cnt[str[i] - 'a'] -= 2;
        }
    }
 
    for(int i = 0, m = strv.size(); i < m; i++) strv.push_back(strv[i]);
 
    for(int i = 0; i < n; i++) indx[strv[i] - 'a'].push_back(i + 1);
 
    for(int i = 0; i < 26; i++) reverse(indx[i].begin(), indx[i].end());
    int mx=0;
    for(int i = 0; i < n; i++){
        v.push_back(indx[str[i] - 'a'].back());
        indx[str[i] - 'a'].pop_back();
        mx = max(mx, v[i]);
    }
    int Tree[6 * mx];
     memset(Tree, 0, sizeof(Tree));
    for(auto i : v){
        ans += query(Tree, 1, 1, mx, i + 1, mx);
        up(Tree, 1, 1, mx, i);
    }
 
    cout << ans;
}

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