Submission #683933

#	Time	Username	Problem	Language	Result	Execution time	Memory
683933		abc864197532	Monochrome Points (JOI20_monochrome)	C++17	4 / 100	1 ms	212 KiB

monochrome

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define pii pair<int,int>
#define all(x) x.begin(), x.end()

int main() {
	ios::sync_with_stdio(false), cin.tie(0);
	int n;
	string s;
	cin >> n >> s;
	vector <pii> a;
	for (int i = 0; i < n; ++i) {
		if (s[i] == s[i + n]) {
			a.emplace_back(i, s[i] == 'B' ? 1 : 0);
		}
	}
	ll ans = 0;
	while (!a.empty()) {
		pii mn = {1 << 30, -1};
		int sz = a.size();
		for (int i = 0; i < sz; ++i) {
			if (a[i].second != a[(i + 1) % sz].second) {
				int len = abs(a[i].first - a[(i + 1) % sz].first);
				mn = min(mn, {min(len, n - len), i});
			}
		}
		ans += mn.first;
		int x = mn.second;
		int y = (x + 1) % sz;
		if (x > y) {
			swap(x, y);
		}
		a.erase(a.begin() + y);
		a.erase(a.begin() + x);
	}
	cout << 1ll * n * (n - 1) / 2 - ans << '\n';
}

• Subtask 1: 4 / 4
• Subtask 2: 0 / 21
• Subtask 3: 0 / 10
• Subtask 4: 0 / 65