Submission #1150875

#	Time	Username	Problem	Language	Result	Execution time	Memory
1150875		AmirAli_H1	Chorus (JOI23_chorus)	C++20	61 / 100	647 ms	1536 KiB

chorus

// In the name of Allah

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

typedef		long long int			ll;
typedef		long double				ld;
typedef		pair<int, int>			pii;
typedef		pair<ll, ll>			pll;
typedef		complex<ld>				cld;

#define		all(x)					(x).begin(),(x).end()
#define		len(x)					((ll) (x).size())
#define		F						first
#define		S						second
#define		pb						push_back
#define		sep						' '
#define		endl					'\n'
#define		Mp						make_pair
#define		kill(x)					cout << x << '\n', exit(0)
#define		set_dec(x)				cout << fixed << setprecision(x);
#define		file_io(x,y)			freopen(x, "r", stdin); freopen(y, "w", stdout);
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int maxn = 5000 + 4;
const ll oo = 1e18 + 4;
const ll inf = 1e12 + 4;

int n, k; string s;
vector<ll> ls; pll dp[maxn];

void cal(ll valx) {
	dp[0] = Mp(0, 0);
	for (int j = 1; j <= n; j++) dp[j] = Mp(oo, oo);
	for (int j = 0; j < n; j++) {
		ll x = valx;
		for (int R = j + 1; R <= n; R++) {
			x += max(0ll, (ls[R - 1] - j));
			dp[R] = min(dp[R], Mp(dp[j].F + x, dp[j].S + 1));
		}
	}
}

void solve() {
	cin >> n >> k >> s;
	ll res = 0; int x = 0;
	for (int i = 0; i < (2 * n); i++) {
		if (s[i] == 'B') x++;
		else ls.pb(x);
	}
	for (int i = 0; i < n; i++) {
		if (ls[i] > i) {
			res += (ls[i] - i); ls[i] = i;
		}
	}
	
	ll l = -1, r = inf;
	while (r - l > 1) {
		ll mid = (l + r) / 2; cal(mid);
		if (dp[n].S > k) l = mid;
		else r = mid;
	}
	cal(r);
	cout << res + (dp[n].F - (k * r)) << endl;
}

int main() {
	ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	
	int T = 1;
	while (T--) {
		solve();
	}
	
	return 0;
}

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