Submission #972982

#	Time	Username	Problem	Language	Result	Execution time	Memory
972982		bonk	Watching (JOI13_watching)	C++17	100 / 100	235 ms	16296 KiB

watching

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

const int INF = 1e8;
const int MAX_N = 2005;
int dp[MAX_N][MAX_N], a[MAX_N], nxtP[MAX_N], nxtQ[MAX_N];
int N, P, Q;

int f(int idx, int remQ){
    if(remQ < 0) return INF;
    if(idx > N) return 0;
    auto &cur = dp[idx][remQ];

    if(cur != -1) return cur;

    cur = min(f(nxtP[idx], remQ) + 1, f(nxtQ[idx], remQ - 1));
    return cur;
}

bool check(int x){
    int j = 2, k = 2;
    for(int i = 1; i <= N; i++){
        while(j <= N && a[j] - a[i] + 1 <= x) j++;
        while(k <= N && a[k] - a[i] + 1 <= 2*x) k++;
        nxtP[i] = j;
        nxtQ[i] = k;
    }

    memset(dp, -1, sizeof(dp));
    return (f(1, Q) <= P);
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> N >> P >> Q;
    P = min(P, N); Q = min(Q, N);

    for(int i = 1; i <= N; i++) cin >> a[i];
    sort(a + 1, a + N + 1);

    ll ans = -1, l = 1, r = 1e9;

    while(l <= r){
        int mid = (l + r)/2;
        if(check(mid)){
            ans = mid;
            r = mid - 1;
        } else{
            l = mid + 1;
        }
    }

    cout << ans << '\n';

    return 0;
}

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