Submission #49599

#	Time	Username	Problem	Language	Result	Execution time	Memory
49599		mra2322001	Watching (JOI13_watching)	C++14	100 / 100	367 ms	16560 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;
typedef pair <int, int> pii;

int n, p, q, a[N];

ostream& operator << (ostream &os, pii yu){
    cout << yu.first << " " << yu.second;
}

istream& operator >> (istream &is, pii &yu){
    cin >> yu.first >> yu.second;
}

int f[N][N], d1[N], d2[N];
bool check(int mid){
    memset(f, -1, sizeof(f));
    memset(d1, 0, sizeof(d1));
    memset(d2, 0, sizeof(d2));
    f1(i, n){
        int k = lower_bound(a + 1, a + n + 1, a[i] - mid + 1) - a; --k;
        d1[i] = k;
        k = lower_bound(a + 1, a + n + 1, a[i] - 2*mid + 1) - a; --k;
        d2[i] = k;
    }
    f0(j, q + 1) f[0][j] = p;
    f1(i, n){
        f0(j, q + 1){
            if(j == 0){
                int k = d1[i];
                /// k + 1 -> i
                if(f[k][j] > 0){
                    f[i][j] = f[k][j] - 1;
                }
            }
            else{
                int k = d1[i];
                /// k + 1 -> i
                if(f[k][j] > 0){
                    f[i][j] = f[k][j] - 1;
                }
                k = d2[i];
                f[i][j] = max(f[i][j], f[k][j - 1]);
            }
        }
    }
    return (f[n][q] >= 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 + 2, ans = -1;
    while(l <= r){
        int mid = (l + r)/2;
        if(check(mid)) ans = mid, r = mid - 1;
        else l = mid + 1;
    }
    cout << ans;
}

Compilation message (stderr)

watching.cpp: In function 'std::ostream& operator<<(std::ostream&, pii)':
watching.cpp:14:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
watching.cpp: In function 'std::istream& operator>>(std::istream&, pii&)':
watching.cpp:18:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^

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