Submission #584521

#	Time	Username	Problem	Language	Result	Execution time	Memory
584521		stevancv	Watching (JOI13_watching)	C++14	100 / 100	672 ms	16224 KiB

watching

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 1e5 + 2;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n, p, q;
    cin >> n >> p >> q;
    smin(p, n);
    smin(q, n);
    vector<int> a(n + 1);
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    sort(a.begin(), a.end());
    auto Can = [&] (int o) {
        vector<int> x(n + 1), y(n + 1);
        int j = 1;
        for (int i = 1; i <= n; i++) {
            while (a[i] - a[j] >= o) j++;
            x[i] = j;
        }
        j = 1;
        for (int i = 1; i <= n; i++) {
            while (a[i] - a[j] >= 2 * o) j++;
            y[i] = j;
        }
        vector<vector<int>> dp(n + 1, vector<int>(p + 1, 1e9));
        dp[0][0] = 0;
        for (int i = 1; i <= n; i++) {
            for (int j = 0; j <= p; j++) {
                if (j > 0) smin(dp[i][j], dp[x[i] - 1][j - 1]);
                if (dp[y[i] - 1][j] != 1e9) smin(dp[i][j], dp[y[i] - 1][j] + 1);
            }
        }
        for (int j = 0; j <= p; j++) if (dp[n][j] <= q) return true;
        return false;
    };
    int l = 1; int r = 1e9;
    int ans = 1e9;
    while (l <= r) {
        int mid = l + r >> 1;
        if (Can(mid)) {
            ans = mid;
            r = mid - 1;
        }
        else l = mid + 1;
    }
    cout << ans << en;
    return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:49:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   49 |         int mid = l + r >> 1;
      |                   ~~^~~

• Subtask 1: 50 / 50
• Subtask 2: 50 / 50