Submission #1076017

#	Time	Username	Problem	Language	Result	Execution time	Memory
1076017		andrewp	Watching (JOI13_watching)	C++14	100 / 100	186 ms	16228 KiB

watching

//Dedicated to my love, ivaziva
#include <bits/stdc++.h>
using namespace std;

using pii = pair<int, int>;
using ll = int64_t;

#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define dbg(x) cerr << #x << ": " << x << '\n'; 

constexpr int N = 2e3 + 5, W = (int)1e9 + 10;
int n, p, q, a[N], dp[N][N];

bool check(int w) {     
    for (int i = 0; i <= n; i++) {
        for (int j = 0; j <= n; j++) {
            dp[i][j] = W;
        }
    }
    dp[0][0] = 0;
    int f = 0, s = 0;
    for (int i = 1; i <= n; i++) {
        while (a[i] >= a[f + 1] + w) {
            f++;
        }
        while (a[i] >= a[s + 1] + 2 * w) {
            s++;
        }
        for (int j = 0; j <= n; j++) {
            dp[i][j] = dp[f][j] + 1;
            if (j) {
                dp[i][j] = min(dp[i][j], dp[s][j - 1]);
            }
        }
    }
    for (int i = 0; i <= min(n, q); i++) {
        if (dp[n][i] <= p) {
            return true;
        }
    }
    return false;
}

int32_t main() {
    ios::sync_with_stdio(false); cin.tie(nullptr);
    cout.tie(nullptr); cerr.tie(nullptr);

    cin >> n >> p >> q;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    sort(a + 1, a + n + 1);
    int l = 1, r = W, ans = W;
    while (l <= r) {
        int mid = l + r >> 1;
        if (check(mid)) {
            r = mid - 1;
            ans = mid;
        } else {
            l = mid + 1;
        }
    }
    cout << ans << '\n';
    return 0;   
}

Compilation message (stderr)

watching.cpp: In function 'int32_t main()':
watching.cpp:56:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   56 |         int mid = l + r >> 1;
      |                   ~~^~~

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