Submission #1045013

#	Time	Username	Problem	Language	Result	Execution time	Memory
1045013		Beerus13	Ekoeko (COCI21_ekoeko)	C++14	110 / 110	8 ms	3868 KiB

Main

#include<bits/stdc++.h>
using namespace std;
#define FOR(i, a, b)  for(int i = (a), _b = (b); i <= _b; ++i)
#define FORD(i, b, a) for(int i = (b), _a = (a); i >= _a; --i)
#define REP(i, a, b)  for(int i = (a), _b = (b); i < _b;  ++i)
#define REPD(i, b, a) for(int i = (b), _a = (a); i > _a;  --i)
#define MASK(i) (1LL << (i))
#define BIT(mask, i) (((mask) >> (i)) & 1)
#define __builtin_popcount __builtin_popcountll
#define all(v) v.begin(), v.end()
#define ll long long
#define ull unsigned long long
#define lb long double
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second
#define cd complex<double>
#define int ll
const double PI = acos(-1);
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll Rand(ll l, ll r) {return l + rng() % (r - l + 1);}

// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
// typedef tree<pii, null_type,less<pii>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
// - insert(x),erase(x)
// - find_by_order(k): return iterator to the k-th smallest element
// - order_of_key(x): the number of elements that are strictly smaller

template<class X, class Y>
    bool minimize(X &x, const Y &y) {
        if (x > y) {
            x = y;
            return true;
        } else return false;
    }
template<class X, class Y>
    bool maximize(X &x, const Y &y) {
        if (x < y) {
            x = y;
            return true;
        } else return false;
    }
template<class T>
    T Abs(const T &x) {
        return (x < 0 ? -x : x);
    }

const int mod = 1e9 + 7;
const int N = 2e5 + 5;

struct fenwicktree {
    int n;
    vector<int> a;
    fenwicktree(int _n) {
        n = _n;
        a.assign(n + 1, 0);
    }

    void update(int i, int val) {
        for(; i; i -= i & -i) a[i] += val;
    }

    int get(int i) {
        int res(0);
        for(; i <= n; i += i & -i) res += a[i];
        return res;
    }
};

vector<int> pos[26];

void process() {
    int n; string s;
    cin >> n >> s; s = ' ' + s;
    vector<int> cnt(26, 0), cur(26, 0);
    vector<bool> Left(2 * n + 5, 0);
    FOR(i, 1, 2 * n) cnt[s[i] - 'a']++;
    FOR(i, 1, 2 * n) {
        int c = s[i] - 'a';
        cur[c]++;
        Left[i] = (cur[c] <= cnt[c] / 2);
    }
    ll ans = 0;
    int res(0);
    string nw = " ";
    FOR(i, 1, 2 * n) if(Left[i]) {
        nw += s[i];
        ++res;
        ans += i - res;
    }

    FOR(i, 1, 2 * n) if(!Left[i]) nw += s[i];
    vector<int> a;
    FORD(i, n, 1) pos[nw[i] - 'a'].push_back(i);
    FOR(i, n + 1, 2 * n) {
        a.push_back(pos[nw[i] - 'a'].back());
        pos[nw[i] - 'a'].pop_back();
    }
    fenwicktree bit(n);
    for(int &x : a) {
        ans += bit.get(x);
        bit.update(x, 1);
    }
    cout << ans << '\n';
}

signed main() {
    if(fopen("eko.inp","r")) {
        freopen("eko.inp","r",stdin);
        freopen("eko.out","w",stdout);
    }
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    // clock_t start = clock()

    int ntests = 1;
    // cin >> ntests;
    while(ntests--) process();

    // cerr << "Time elapsed: " << clock() - start << " ms!\n";
    return 0;
}
// https://oj.uz/problem/submit/COCI21_ekoeko

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:112:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  112 |         freopen("eko.inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
Main.cpp:113:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  113 |         freopen("eko.out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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