Submission #977277

#	Time	Username	Problem	Language	Result	Execution time	Memory
977277		LOLOLO	Watching (JOI13_watching)	C++17	100 / 100	218 ms	17748 KiB

watching

#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
 
#define           f    first
#define           s    second
#define           pb    push_back
#define           ep    emplace
#define           eb    emplace_back
#define           lb    lower_bound
#define           ub    upper_bound
#define       all(x)    x.begin(), x.end()
#define      rall(x)    x.rbegin(), x.rend()
#define   uniquev(v)    sort(all(v)), (v).resize(unique(all(v)) - (v).begin())
#define     mem(f,x)    memset(f , x , sizeof(f))
#define        sz(x)    (int)(x).size()
#define  __lcm(a, b)    (1ll * ((a) / __gcd((a), (b))) * (b))
#define          mxx    *max_element
#define          mnn    *min_element
#define    cntbit(x)    __builtin_popcountll(x)
#define       len(x)    (int)(x.length())
 
const int N = 2e3 + 100;
int a[N], n, p, q;
int f[N][N];

bool check(int w) {
    mem(f, 0x3f);
    f[0][0] = 0;
    for (int i = 1; i <= n; i++) {
        int l1 = lower_bound(a + 1, a + 1 + n, a[i] - w + 1) - a;
        int l2 = lower_bound(a + 1, a + 1 + n, a[i] - 2 * w + 1) - a;
        for (int j = 0; j <= n; j++) {
            if (j) {
                f[i][j] = min(f[i][j], f[l2 - 1][j - 1]);
            } 

            f[i][j] = min(f[i][j], f[l1 - 1][j] + 1);
        }
    }

    for (int i = 1; i <= q; i++) {
        if (f[n][i] <= p)
            return 1;
    }

    return 0;
}

int main() {
    ios_base::sync_with_stdio(false); 
    cin.tie(NULL);
    cout.tie(NULL);

    cin >> n >> p >> q;

    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }

    sort(a + 1, a + n + 1);

    int l = 1, r = 1e9, m, ans;
    while (l <= r) {
        m = (l + r) / 2;
        if (check(m)) {
            ans = m;
            r = m - 1;
        } else {
            l = m + 1;
        }
    }

    cout << ans << '\n';

    return 0;
} 

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:74:20: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   74 |     cout << ans << '\n';
      |                    ^~~~

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