Submission #1261847

#	Time	Username	Problem	Language	Result	Execution time	Memory
1261847		tminh	Watching (JOI13_watching)	C++20	0 / 100	26 ms	16196 KiB

watching

#include "bits/stdc++.h"
using namespace std;

#define task ""
#define ll long long
#define endl '\n'
#define fi first
#define se second
#define vall(a) (a).begin(), (a).end()
#define sze(a) (int)a.size()
#define pii pair<int, int>
#define pll pair<ll, ll>


#define ep emplace_back
#define pb push_back
#define pf push_front


const ll mod = 1e9 + 7;
const int N = 2005;
const int oo = 1e9;

bool START;

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

int dp[N][N];
ll nxtp[N], nxtq[N];

int f(int pos, int need) {
	if (pos == n + 1) return 0;
	
	int &res = dp[pos][need];
	if (res != -1) return res;
	
	res = oo;
	
	int pos_ = nxtq[pos];
	if (need < q && pos_ != pos) res = min(res, f(pos_, need + 1));
	
	pos_ = nxtp[pos];
	if (pos_ != pos) res = min(res, f(pos_, need) + 1);
	
	return res; 
}

bool check(int x) {
	for (int i = 1; i <= n; ++i) {
		nxtp[i] = upper_bound(a + 1, a + 1 + n, a[i] + x - 1) - a;
		nxtq[i] = upper_bound(a + 1, a + 1 + n, a[i] + (x << 1) - 1) - a;
	}
	memset(dp, -1, sizeof(dp));
	return (f(1, 0) <= p);
}

ll cnp() {
	ll l = 1, r = oo, ans = oo;
	while(l <= r) {
		ll mid = (l + r) >> 1;
		if (check(mid)) {
			ans = mid;
			r = mid - 1;
		} else {
			l = mid + 1;
		}
	}
	return ans;
}

inline void solve() {
	cout << cnp();
}


inline void input() {
    cin >> n >> p >> q;
    for (int i = 1; i <= n; ++i) cin >> a[i];
    return solve();
}
bool END;

int main() {
    if(fopen(task ".inp", "r")) {
        freopen(task ".inp", "r", stdin);
        freopen(task ".out", "w", stdout);
    }
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);

    input();
    
    
    cerr << endl << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << 's' << endl;
    cerr << "Memory: " << fabs ((&END - &START)) / 1048576.0 << "MB\n";
    return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:86:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   86 |         freopen(task ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
watching.cpp:87:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   87 |         freopen(task ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 50
• Subtask 2: 0 / 50