Submission #1153024

#	Time	Username	Problem	Language	Result	Execution time	Memory
1153024		AmirAli_H1	Sparklers (JOI17_sparklers)	C++20	50 / 100	16 ms	1352 KiB

sparklers

// 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 = 1000 + 4;

int n, k; ll t;
ll A[maxn]; bool dp[maxn][maxn];

ll get_val(int i, int j, ll tx) {
	return (tx * (j - i + 1)) - (A[j] - A[i]);
}

bool ok(ll x) {
	ll tx = (t * x);
	if (tx >= A[n - 1]) return 1;
	for (int i = k; i >= 0; i--) {
		for (int j = k; j < n; j++) {
			if (i == k && j == k) {
				dp[i][j] = 1;
			}
			else {
				dp[i][j] = 0;
				if (i + 1 <= k) {
					if (get_val(i + 1, j, tx) >= (A[i + 1] - A[i])) dp[i][j] |= dp[i + 1][j];
				}
				if (j - 1 >= k) {
					if (get_val(i, j - 1, tx) >= (A[j] - A[j - 1])) dp[i][j] |= dp[i][j - 1];
				}
			}
		}
	}
	return dp[0][n - 1];
}

void solve() {
	cin >> n >> k >> t; k--; t *= 2;
	for (int i = 0; i < n; i++) {
		cin >> A[i];
	}

	ll l = -1, r = (A[n - 1] / t) + 2;
	while (r - l > 1) {
		ll mid = (l + r) / 2;
		if (ok(mid)) r = mid;
		else l = mid;
	}
	cout << 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: 30 / 30
• Subtask 2: 20 / 20
• Subtask 3: 0 / 50