Submission #880364

#	Time	Username	Problem	Language	Result	Execution time	Memory
880364		tsumondai	Ekoeko (COCI21_ekoeko)	C++14	110 / 110	6 ms	4584 KiB

Main

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

#define int long long
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define foru(i, l, r) for(int i = l; i <= r; i++)
#define ford(i, r, l) for(int i = r; i >= l; i--)
#define __TIME  (1.0 * clock() / CLOCKS_PER_SEC)

typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<ii, ii> iiii;

const int N = 1e5 + 5;

const int oo = 1e9, mod = 1e9 + 7;

int n, cnt[30], p[N], ans = 0;
string s, a, b;
vector<int> t1[30], t2[30];

int bittree[N];

void update(int i) {
	for (++i; i <= n; i += i & -i)
		++bittree[i];
}

int getSum(int i) {
	int r = 0;
	for (++i; i; i -= i & -i)
		r += bittree[i];
	return r;
}

void process() {
	cin >> n >> s;
	for (auto c : s) cnt[c - 'a']++;
	foru(i, 0, 25) cnt[i] /= 2;
	int x = 0;
	foru(i, 0, 2 * n - 1) {
		if (cnt[s[i] - 'a']) {
			a += s[i], ans += x; cnt[s[i] - 'a']--;
		} else {
			b += s[i]; x++;
		}
	}

	foru(i, 0, n - 1) {
		t1[a[i] - 'a'].pb(i);
		t2[b[i] - 'a'].pb(i);
	}

	foru(i, 0, 25) {
		for (int j = 0; j < t1[i].size(); ++j) {
			p[t2[i][j]] = t1[i][j];
		}
	}

	foru(i, 0, n - 1) {
		ans += i - getSum(p[i]);
		update(p[i]);
	}

	cout << ans;


	return;
}

signed main() {
	cin.tie(0)->sync_with_stdio(false);
	//freopen(".inp", "r", stdin);
	//freopen(".out", "w", stdout);
	process();
	cerr << "Time elapsed: " << __TIME << " s.\n";
	return 0;
}

/*
Xét các trường hợp đặc biệt
Kiểm tra lại input/output
Cố gắng trâu
Lật ngược bài toán
Keep calm and get VOI
Flow:

*/

Compilation message (stderr)

Main.cpp: In function 'void process()':
Main.cpp:58:21: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   58 |   for (int j = 0; j < t1[i].size(); ++j) {
      |                   ~~^~~~~~~~~~~~~~

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