Submission #931570

# Submission time Handle Problem Language Result Execution time Memory
931570 2024-02-22T04:54:19 Z Baizho Watching (JOI13_watching) C++14
100 / 100
228 ms 17240 KB
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
  
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
 
// #pragma GCC optimize("Ofast,unroll-loops,fast-math")
// #pragma GCC target("popcnt")
 
 
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll,ll> pll;
 
#define sz size()
#define ff first
#define ss second
#define all(a) a.begin(),a.end()
#define pb push_back
 
const int mod = ll(1e9)+7; //(b + (a%b)) % b (to mod -1%(10^9+7) correctly in c++ its -1 but its suppose to be 10^9+6
const ll MOD = 998244353;  // (a%mod)*(binpow(b,mod-2,mod) = (a/b)%mod
const int N = ll(2e3)+100;
const int M = ll(2e5) + 100;
const long long inf = 5e18;
const long double eps = 1e-15L;
 
ll lcm(ll a, ll b) { return (a / __gcd(a,b))*b; }
 
ll binpow(ll a, ll b, ll m) { ll res=1; a %= m; while(b>0){ if(b&1)res=(res * a) % m; a=(a * a) % m; b/=2; } return res%m;}
 
void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }
 
int n, p, q, a[N], dp[N][N], pos1[N], pos2[N];

bool check(int w) {
	dp[0][0] = 0;
	int p1 = 1, p2 = 1;
	for(int i = 1; i <= n; i ++) {
		while(p1 < i && a[p1] < a[i] - w + 1) p1 ++;
		while(p2 < i && a[p2] < a[i] - 2 * w + 1) p2 ++;
		pos1[i] = p1;
		pos2[i] = p2;
//		cout<<i<<" "<<p1<<" "<<p2<<"\n";
	}
	for(int i = 1; i <= n; i ++) {
		for(int kp = 0; kp <= p; kp ++) {
			dp[i][kp] = q + 1;
			// prefix i, and using kp, how many minimum q's do we need
			// use kp
			if(kp - 1 >= 0) dp[i][kp] = min(dp[i][kp], dp[pos1[i] - 1][kp - 1]);
			// use q
			dp[i][kp] = min(dp[i][kp], dp[pos2[i] - 1][kp] + 1);
		}
	}
	for(int i = 0; i <= p; i ++) if(dp[n][i] <= q) return true;
	return false;
}

void Baizho() {
	cin>>n>>p>>q;
	for(int i = 1; i <= n; i ++) {
		cin>>a[i];
	}
	sort(a + 1, a + n + 1);
	p = min(p, n);
	q = min(q, n);
	
	int l = 1, r = 1e9;
//	int l = 3, r = 3;
	while(l <= r) {
		int mid = (l + r) / 2;
		if(check(mid)) r = mid - 1;
		else l = mid + 1;
	}
	cout<<r + 1<<"\n";
	
	
}
 
signed main() {		
// 	Freopen("nondec");
    ios_base::sync_with_stdio(false);   
    cin.tie(0);cout.tie(0); 
//   	precalc();
   	
    int ttt = 1;
//    cin>>ttt;
 
    for(int i=1; i<=ttt; i++) {Baizho(); }
}

Compilation message

watching.cpp: In function 'void Freopen(std::string)':
watching.cpp:35:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 | void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }
      |                           ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
watching.cpp:35:76: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 | void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }
      |                                                                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Verdict Execution time Memory Grader output
1 Correct 1 ms 2396 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 344 KB Output is correct
4 Correct 2 ms 2392 KB Output is correct
5 Correct 1 ms 2396 KB Output is correct
6 Correct 1 ms 2392 KB Output is correct
7 Correct 1 ms 2548 KB Output is correct
8 Correct 1 ms 2396 KB Output is correct
9 Correct 1 ms 2396 KB Output is correct
10 Correct 1 ms 2396 KB Output is correct
11 Correct 1 ms 2396 KB Output is correct
12 Correct 1 ms 2396 KB Output is correct
13 Correct 1 ms 2396 KB Output is correct
14 Correct 1 ms 2396 KB Output is correct
15 Correct 1 ms 2396 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 3 ms 16968 KB Output is correct
2 Correct 0 ms 344 KB Output is correct
3 Correct 170 ms 16988 KB Output is correct
4 Correct 218 ms 16984 KB Output is correct
5 Correct 11 ms 16732 KB Output is correct
6 Correct 228 ms 17032 KB Output is correct
7 Correct 4 ms 16732 KB Output is correct
8 Correct 18 ms 16988 KB Output is correct
9 Correct 88 ms 17036 KB Output is correct
10 Correct 217 ms 16984 KB Output is correct
11 Correct 14 ms 17240 KB Output is correct
12 Correct 114 ms 17044 KB Output is correct
13 Correct 5 ms 16984 KB Output is correct
14 Correct 5 ms 16984 KB Output is correct
15 Correct 5 ms 16988 KB Output is correct