Submission #1296578

#	Time	Username	Problem	Language	Result	Execution time	Memory
1296578		baodat	Watching (JOI13_watching)	C++20	100 / 100	158 ms	16320 KiB

watching

// problem1.cpp
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define FOR(i, l, r) for(int i = l; i <= r; i++)
#define FORD(i, l, r) for(int i = l; i >= r; i--)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sp(x) setprecision(x) << fixed
#define db double
#define ldb long double
#define ff first
#define ss second
#define pb push_back
#define ins insert
const int N = 2e3 + 5;
int n, p, q, a[N];
bool check(int w){     
    vector<int> small_cam(n + 1), big_cam(n + 1);
    function<int(int)> find_pos = [&](int x){
        int l = 1, r = n, ans = n + 1;
        while(l <= r){
            int m = (l + r) >> 1;
            if(a[m] <= x){
                ans = m;
                l = m + 1;
            }
            else r = m - 1;
        }
        return ans;
    };
    FOR(i, 1, n){
        small_cam[i] = find_pos(a[i] + w - 1);
        big_cam[i] = find_pos(a[i] + 2 * w - 1);
        //cerr << "small[" << i << "]: " << small_cam[i] << "\n";
        //cerr << "big[" << i << "]: " << big_cam[i] << "\n";
    }
    vector<vector<int>> dp(p + 5, vector<int>(q + 5, 0));
    FOR(i, 0, p)FOR(j, 0, q){
        if(i > 0)dp[i][j] = max(dp[i][j], small_cam[dp[i - 1][j] + 1]);
        if(j > 0)dp[i][j] = max(dp[i][j], big_cam[dp[i][j - 1] + 1]);
        if(dp[i][j] >= n) return true;
    }
    return dp[p][q] == n;
}
void solve(){
    cin >> n >> p >> q;
    p = min(n, p);
    q = min(n, q);
    FOR(i, 1, n) cin >> a[i];
    sort(a + 1, a + 1 + n);
    int l = 1, r = 1e9, ans = r;
    //check(4);
    while(l <= r){
        int m = (l + r) >> 1;
        if(check(m)){
            ans = m;
            r = m - 1;
        }
        else l = m + 1;
    }
    cout << ans << "\n";
}

signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;
    //cin >> t;
    while(t--){
        solve();
    }
    return 0;
}

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