Submission #917132

#	Time	Username	Problem	Language	Result	Execution time	Memory
917132		allvik	Sparklers (JOI17_sparklers)	C++17	0 / 100	1 ms	2396 KiB

sparklers

#include <iostream>
#include <vector>

using namespace std;
#define int long long
const int MAXN = 5000;
int dp[MAXN][MAXN];
int t;

bool check(int n, int k, vector <int>& a, int s) {
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            dp[i][j] = 0;
        }
    }
    dp[k][k] = 1;
    for (int len = 1; len <= n; ++len) {
        for (int l = 0; l + len - 1 < n; ++l) {
            int r = l + len - 1;
            if (dp[l][r] == 0) continue;
            if (r < n - 1 && (a[r + 1] - a[l]) <= (r - l + 1) * t * 2 * s) dp[l][r + 1] = 1;
            if (l && (a[r] - a[l - 1]) <= (r - l + 1) * t * 2 * s) dp[l - 1][r] = 1;
        }
    }
    return dp[0][n - 1];
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int n, k;
    cin >> n >> k >> t;
    vector <int> a(n);
    for (int i = 0; i < n; ++i) cin >> a[i];
    if (a[n - 1] == a[0]) {
        cout << 0;
        return 0;
    }
    int l = 0;
    int r = a.back() - a[0];
    while (r - l > 1) {
        int m = (l + r) / 2;
        if (check(n, k, a, m)) r = m;
        else l = m;
    }
    cout << r;
    return 0;
}

/*
3 2 50
0
200
300

3 2 10
0
200
300

20 6 1 0
2
13
27
35
46
63
74
80
88
100
101
109
110
119
138
139
154
172
192
 */

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