Submission #227708

#	Time	Username	Problem	Language	Result	Execution time	Memory
227708		PeppaPig	Watching (JOI13_watching)	C++14	100 / 100	260 ms	16248 KiB

watching

#include <bits/stdc++.h>

using namespace std;

const int N = 2e3+5;

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

bool f(int mid) {
    fill_n(dp[0], N * N, 1e9);

    int l1 = 1, l2 = 1;
    dp[0][0] = 0;
    for(int i = 1; i <= n; i++) {
        while(pos[i] - pos[l1] >= mid) ++l1;
        while(pos[i] - pos[l2] >= 2 * mid) ++l2;

        for(int j = 0; j <= n; j++) {
            dp[i][j] = dp[l2 - 1][j] + 1;
            if(j) dp[i][j] = min(dp[i][j], dp[l1 - 1][j - 1]);
        }
    }
    for(int i = 0; i <= p; i++) if(dp[n][i] <= q)
        return true;
    return false;
}

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

    int l = 1, r = 1e9;
    while(l < r) {
        int mid = (l + r) >> 1;
        if(f(mid)) r = mid;
        else l = mid + 1;
    }
    printf("%d\n", r);

    return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:30:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d %d", &n, &p, &q);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
watching.cpp:31:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i = 1; i <= n; i++) scanf("%d", pos + i);
                                 ~~~~~^~~~~~~~~~~~~~~

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