#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define endl '\n'
#define pb push_back
#define conts continue
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "YES" << endl
#define no cout << "NO" << endl
#define ff first
#define ss second
#define ceil2(x,y) ((x+y-1) / (y))
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#ifndef ONLINE_JUDGE
#define debug(x) cout << #x <<" = "; print(x); cout << endl
#else
#define debug(x)
#endif
#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define trav(i,a) for(auto &i : a)
bool iseven(ll n) {if ((n & 1) == 0) return true; return false;}
void print(ll t) {cout << t;}
void print(int t) {cout << t;}
void print(string t) {cout << t;}
void print(char t) {cout << t;}
void print(double t) {cout << t;}
void print(ld t) {cout << t;}
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(pair <T, V> p) {cout << "{"; print(p.ff); cout << ","; print(p.ss); cout << "}";}
template <class T> void print(vector <T> v) {cout << "[ "; for (T i : v) {print(i); cout << " ";} cout << "]";}
template <class T> void print(set <T> v) {cout << "[ "; for (T i : v) {print(i); cout << " ";} cout << "]";}
template <class T> void print(multiset <T> v) {cout << "[ "; for (T i : v) {print(i); cout << " ";} cout << "]";}
template <class T, class V> void print(map <T, V> v) {cout << "[ "; for (auto i : v) {print(i); cout << " ";} cout << "]";}
void usaco(string filename) {
freopen((filename + ".in").c_str(), "r", stdin);
freopen((filename + ".out").c_str(), "w", stdout);
}
const int MOD = 1e9 + 7;
const int maxn = 1e5 + 5;
const int inf1 = 1e9 + 5;
const ll inf2 = ll(1e18) + 5;
ll dp[2005][2005];
void solve(int test_case)
{
// referred to this: https://github.com/SpeedOfMagic/CompetitiveProgramming/blob/master/JOIOC/13-watching.cpp
ll n, p, q; cin >> n >> p >> q;
vector<ll> a(n + 5);
rep1(i, n) cin >> a[i];
if(p + q >= n){
cout << 1 << endl;
return;
}
sort(a.begin() + 1, a.begin() + n + 1);
auto check = [&](ll k) {
// dp[i][j] = min no.of large cameras required to cover all events from [1..i] using j small cameras
// large[i] = right most position for which a[pos] < a[i] - (2 * k) + 1
// small[i] = right most position for which a[pos] < a[i] - k + 1
rep(i, n + 5) rep(j, p + 5) dp[i][j] = inf2;
vector<ll> large(n + 5), small(n + 5);
rep1(i, n) {
auto it = lower_bound(a.begin() + 1, a.begin() + n + 1, a[i] - (2 * k) + 1);
ll pos = max(ll(it - a.begin() - 1), 0ll);
large[i] = pos;
}
rep1(i, n) {
auto it = lower_bound(a.begin() + 1, a.begin() + n + 1, a[i] - k + 1);
ll pos = max(ll(it - a.begin() - 1), 0ll);
small[i] = pos;
}
dp[0][0] = 0;
rep1(i, n) {
rep(j, p + 1) {
// place large cam
ll pos1 = large[i];
dp[i][j] = min(dp[i][j], dp[pos1][j] + 1);
// place small cam
if (j) {
ll pos2 = small[i];
dp[i][j] = min(dp[i][j], dp[pos2][j - 1]);
}
}
}
rep(j, p + 1) {
if (dp[n][j] <= q) {
return true;
}
}
return false;
};
ll l = 1, r = inf1;
ll ans = inf2;
while (l <= r) {
ll mid = (l + r) / 2;
if (check(mid)) {
ans = min(ans, mid);
r = mid - 1;
}
else {
l = mid + 1;
}
}
cout << ans << endl;
}
int main()
{
fastio;
int t = 1;
// cin >> t;
rep1(i, t) {
solve(i);
}
return 0;
}
Compilation message
watching.cpp: In function 'void usaco(std::string)':
watching.cpp:56:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
56 | freopen((filename + ".in").c_str(), "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
watching.cpp:57:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
57 | freopen((filename + ".out").c_str(), "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
716 KB |
Output is correct |
| 2 |
Correct |
0 ms |
204 KB |
Output is correct |
| 3 |
Correct |
0 ms |
332 KB |
Output is correct |
| 4 |
Correct |
1 ms |
204 KB |
Output is correct |
| 5 |
Correct |
0 ms |
204 KB |
Output is correct |
| 6 |
Correct |
0 ms |
204 KB |
Output is correct |
| 7 |
Correct |
1 ms |
704 KB |
Output is correct |
| 8 |
Correct |
1 ms |
712 KB |
Output is correct |
| 9 |
Correct |
1 ms |
716 KB |
Output is correct |
| 10 |
Correct |
1 ms |
716 KB |
Output is correct |
| 11 |
Correct |
1 ms |
700 KB |
Output is correct |
| 12 |
Correct |
1 ms |
716 KB |
Output is correct |
| 13 |
Correct |
1 ms |
716 KB |
Output is correct |
| 14 |
Correct |
1 ms |
716 KB |
Output is correct |
| 15 |
Correct |
1 ms |
716 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
8 ms |
8524 KB |
Output is correct |
| 2 |
Correct |
1 ms |
204 KB |
Output is correct |
| 3 |
Correct |
1 ms |
332 KB |
Output is correct |
| 4 |
Correct |
1 ms |
332 KB |
Output is correct |
| 5 |
Correct |
1 ms |
332 KB |
Output is correct |
| 6 |
Correct |
1 ms |
332 KB |
Output is correct |
| 7 |
Correct |
13 ms |
8744 KB |
Output is correct |
| 8 |
Correct |
33 ms |
10444 KB |
Output is correct |
| 9 |
Correct |
200 ms |
20304 KB |
Output is correct |
| 10 |
Correct |
408 ms |
31828 KB |
Output is correct |
| 11 |
Correct |
26 ms |
9908 KB |
Output is correct |
| 12 |
Correct |
224 ms |
23860 KB |
Output is correct |
| 13 |
Correct |
14 ms |
8736 KB |
Output is correct |
| 14 |
Correct |
21 ms |
8780 KB |
Output is correct |
| 15 |
Correct |
13 ms |
8780 KB |
Output is correct |
