Submission #1266642

#	Time	Username	Problem	Language	Result	Execution time	Memory
1266642		canhnam357	Ekoeko (COCI21_ekoeko)	C++20	110 / 110	8 ms	2456 KiB

Main

#include <bits/stdc++.h>
using namespace std;
struct fenwick
{
    int n;
    vector<int> bit;
    fenwick() {}
    fenwick(int n)
    {
        this->n = n + 5;
        bit.resize(n + 5);
    }
    void add(int pos, int val)
    {
        while (pos < n)
        {
            bit[pos] += val;
            pos += pos & -pos;
        }
    }
    int get(int pos)
    {
        int ans = 0;
        while (pos)
        {
            ans += bit[pos];
            pos -= pos & -pos;
        }
        return ans;
    }
    int get(int l, int r)
    {
        return get(r) - get(l - 1);
    }
    int find(int k)
    {
        int sum = 0, pos = 0;
        for (int i = __lg(n); i >= 0; i--)
        {
            if (pos + (1 << i) < n && sum + bit[pos + (1 << i)] < k)
            {
                sum += bit[pos + (1 << i)];
                pos += (1 << i);
            }
        }
        return pos + 1;
    }
};
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n;
    cin >> n;
    string s;
    cin >> s;
    string l = "", r = "";
    int cnt[26]{};
    for (char c : s) {
        cnt[c - 'a']++;
    }
    for (int i = 0; i < 26; i++) {
        cnt[i] >>= 1;
    }
    long long ans = 0;
    for (char c : s) {
        if (cnt[c - 'a']) {
            cnt[c - 'a']--;
            l += c;
            ans += r.size();
        }
        else {
            r += c;
        }
    }
    deque<int> pl[26];
    for (int i = 0; i < n; i++) {
        pl[l[i] - 'a'].push_back(i);
    }
    vector<int> p(n);
    for (int i = 0; i < n; i++) {
        p[i] = pl[r[i] - 'a'][0];
        pl[r[i] - 'a'].pop_front();
    }
    fenwick tree(n);
    for (int i : p) {
        i++;
        ans += tree.get(i + 1, n);
        tree.add(i, 1);
    }
    cout << ans;
    return 0;
}

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