Submission #83704

#	Time	Username	Problem	Language	Result	Execution time	Memory
83704		mra2322001	Watching (JOI13_watching)	C++14	100 / 100	383 ms	16568 KiB

watching

#include <bits/stdc++.h>
#define f0(i, n) for(int i(0); i < (n); i++)
#define f1(i, n) for(int i(1); i <= n; i++)

using namespace std;
typedef long long ll;
const int N = 2002;

int n, p, q, a[N], d1[N], d2[N], f[N][N];

bool check(int dist){
    /// f(i, j) den i, dung j camera nho
    f1(i, n){
        d1[i] = lower_bound(a + 1, a + n + 1, a[i] - dist + 1) - a;
        d2[i] = lower_bound(a + 1, a + n + 1, a[i] - 2*dist + 1) - a;
    }
    f0(i, p + 1) f[0][i] = q;
    f1(i, n) f0(j, p + 1) f[i][j] = -1e9;
    f1(i, n){
        f0(j, p + 1){
            if(j==0){
                int x = max(d2[i], 0);
                f[i][j] = f[x - 1][j] - 1;
                continue;
            }
            int x = max(d1[i] - 1, 0);
            f[i][j] = f[x][j - 1];
            x = max(d2[i] - 1, 0);
            f[i][j] = max(f[i][j], f[x][j] - 1);
        }
    }
    f0(j, p + 1) if(f[n][j] >= 0) return 1;
    return 0;
}

int main(){
    ios_base::sync_with_stdio(0);

    cin >> n >> p >> q;
    f1(i, n) cin >> a[i];

    sort(a + 1, a + n + 1);
    if(p + q >= n){
        cout << 1;
        return 0;
    }
    int l = 0, r = 1e9 + 10, ans = 0;
    while(l <= r){
        int mid = (l + r)/2;
        if(check(mid)) r = mid - 1, ans = mid;
        else l = mid + 1;
    }
    cout << ans;
}

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