Submission #1227054

#	Time	Username	Problem	Language	Result	Execution time	Memory
1227054		chaeryeong	Chorus (JOI23_chorus)	C++20	40 / 100	7091 ms	39748 KiB

chorus

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int inf = 1e9;
void solve () {
	int n, k; cin >> n >> k;
	string s; cin >> s;
	int bad = 0;
	int cur = 0;
	for (int i = 0; i < 2 * n; i++) {
		if (s[i] == 'B') {
			cur--;
		} else {
			cur++;
		}
		if (cur < 0) {
			int j = i;
			while (s[j] != 'A') {
				j++;
			}
			bad += j - i;
			swap(s[i], s[j]);
			i--; cur++;
		}
	}
	int dp[n + 1][k + 1] = {};
	vector <int> ii[2];
	ii[0].push_back(0);
	ii[1].push_back(0);
	for (int i = 0; i < 2 * n; i++) {
		ii[s[i] - 'A'].push_back(i + 1);
	}
	for (int i = 1; i <= n; i++) {
		dp[i][0] = inf;
		int l = i;
		while (l > 1 && ii[1][l - 1] > ii[0][i]) {
			l--;
		}
		for (int j = 1; j <= k; j++) {
			dp[i][j] = dp[l - 1][j - 1];
			int prv = ii[0][i];
			int cur = 0;
			for (int p = l - 1; p >= 1; p--) {
				cur += prv - ii[1][p];
				prv--;
				dp[i][j] = min(dp[i][j], cur + dp[p - 1][j - 1]);
			}
		}
	}
	cout << bad + dp[n][k] << '\n';
}	
signed main () {

	ios::sync_with_stdio(0); cin.tie(0);
	int tc = 1; //cin >> tc;
	while (tc--) solve();
}

• Subtask 1: 16 / 16
• Subtask 2: 24 / 24
• Subtask 3: 0 / 21
• Subtask 4: 0 / 26
• Subtask 5: 0 / 13