Submission #745514

#	Time	Username	Problem	Language	Result	Execution time	Memory
745514		sleepntsheep	Watching (JOI13_watching)	C++17	100 / 100	226 ms	16084 KiB

watching

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

const int N = 2005;

int n, p, q, a[N], dp[N][N];

int ok(int w) {
    memset(dp, 63, sizeof dp);
    dp[0][0] = 0;
    for (int i = 1; i <= n; ++i) {
        auto ip = max(0l, upper_bound(a, a+i, a[i] - w) - a - 1);
        auto iq = max(0l, upper_bound(a, a+i, a[i] - 2*w) - a - 1);
        for (int j = 0; j <= p; ++j) {
            if (j) {
                dp[i][j] = min(dp[i][j], dp[ip][j-1]);
            }
            dp[i][j] = min(dp[i][j], dp[iq][j] + 1);
        }
    }
    for (int j = 0; j <= p; ++j)
        if (dp[n][j] <= q) return 1;
    return 0;
}

int main() {
    scanf("%d%d%d", &n, &p, &q);
    p = min(p, n); q = min(q, n);
    for (int i = 1; i <= n; ++i) scanf("%d", a+i);
    sort(a+1, a+n+1);

    int l = 0, r = 1e9+2;
    while (r - l > 1) {
        auto m = (l+r)/2;
        if (ok(m)) r = m;
        else l = m;
    }
    printf("%d", r);

    return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:27:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |     scanf("%d%d%d", &n, &p, &q);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~
watching.cpp:29:39: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |     for (int i = 1; i <= n; ++i) scanf("%d", a+i);
      |                                  ~~~~~^~~~~~~~~~~

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