Submission #83705

#	Time	Username	Problem	Language	Result	Execution time	Memory
83705		mra2322001	Watching (JOI13_watching)	C++14	100 / 100	364 ms	16252 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, a[N], p, q, f[N][N], d1[N], d2[N];

bool check(int dist){
    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) f1(j, p) f[i][j] = -1e9;
    /// f[i][j] den i, dung j camera thi con lai max la bao nhieu
    f1(i, n){
        f0(j, p + 1){
            f[i][j] = f[d2[i] - 1][j] - 1;
            if(j > 0){
                f[i][j] = max(f[i][j], f[d1[i] - 1][j - 1]);
            }
        }
    }
    return f[n][p] >= 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 = 1, r = 1e9 + 5, ans = r;
    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