Submission #931570

#	Time	Username	Problem	Language	Result	Execution time	Memory
931570		Baizho	구경하기 (JOI13_watching)	C++14	100 / 100	228 ms	17240 KiB

watching

#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 (stderr)

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); }
      |                                                                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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