Submission #46288

#	Time	Username	Problem	Language	Result	Execution time	Memory
46288		qoo2p5	Sparklers (JOI17_sparklers)	C++17	50 / 100	206 ms	49788 KiB

sparklers

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int INF = (int) 1e9 + 1e6 + 123;
const ll LINF = (ll) 1e18 + 1e9 + 123;

#define rep(i, s, t) for (auto i = (s); i < (t); ++(i))
#define per(i, s, t) for (auto i = (s); i >= (t); --(i))
#define sz(x) ((int)(x).size())
#define mp make_pair
#define pb push_back

bool mini(auto &x, const auto &y) {
	if (y < x) {
		x = y;
		return 1;
	}
	return 0;
}

bool maxi(auto &x, const auto &y) {
	if (y > x) {
		x = y;
		return 1;
	}
	return 0;
}

void run();

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	run();
	return 0;
}

const int N = 5005;

int n, k;
ll t;
ll x[N], a[N];
bool dp[N][N];

bool check(ll s) {
	memset(dp, 0, sizeof dp);
	dp[k][k] = 1;
	rep(i, 0, n) {
		a[i] = x[i] - 2 * s * t * i;
	}
	rep(len, 2, n + 1) {
		rep(l, 0, n) {
			int r = l + len - 1;
			if (r >= n) {
				break;
			}
			dp[l][r] = ((dp[l + 1][r] || dp[l][r - 1]) && a[l] >= a[r]);
		}
	}
	return dp[0][n - 1];
}

void run() {
	cin >> n >> k >> t;
	k--;
	rep(i, 0, n) {
		cin >> x[i];
	}
	ll left = -1;
	ll right = (x[n - 1] + t) / t;
	
	while (right - left > 1) {
		ll mid = (left + right) / 2;
		if (check(mid)) {
			right = mid;
		} else {
			left = mid;
		}
	}
	
	cout << right << "\n";
}

• Subtask 1: 30 / 30
• Subtask 2: 20 / 20
• Subtask 3: 0 / 50