Submission #912718

#	Time	Username	Problem	Language	Result	Execution time	Memory
912718		Acanikolic	Watching (JOI13_watching)	C++14	100 / 100	659 ms	30476 KiB

watching

#include <bits/stdc++.h>
		 		
#define int long long 
		 
#define pb push_back 
		
#define F first
		 
#define S second
		 
using namespace std;
		 
const int N = 2000 + 10;
		 
const int mod = 1e9 + 7;
		 
const int inf = 1e18;	
 
vector<int>a;
				
bool check(int n,int p,int q,int x) {
	vector<vector<int>>dp(n + 1,vector<int>(p + 2,inf));
	for(int i = 0; i <= p; i++) dp[0][i] = 0;
	int ans1 = 1,ans2 = 1;
	for(int i = 1; i <= n; i++) {
		while(ans1 + 1 <= n && a[i] + x - 1 >= a[ans1 + 1]) ans1 += 1;
		while(ans2 + 1 <= n && a[i] + 2 * x - 1 >= a[ans2 + 1]) ans2 += 1;
		for(int j = 0; j <= p; j++) {
			if(j > 0) dp[i][j] = min(dp[i][j],dp[i - 1][j - 1]);
			//dp[i][j] = min(dp[i][j],dp[i - 1][j] + 1);
			dp[ans1][j + 1] = min(dp[ans1][j + 1],dp[i - 1][j]);
			dp[ans2][j] = min(dp[ans2][j],dp[i - 1][j] + 1);
		}
	}
	if(dp[n][p] <= q) return true;
	return false;
}
																						
signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
	
	int n,p,q;
	cin >> n >> p >> q;
	a.resize(n + 1);
	for(int i = 1; i <= n; i++) cin >> a[i];
  	if(n <= p + q) {
      cout << 1;
      return 0;
    }
	sort(a.begin() + 1,a.end());
	int l = 1,r = 1e9,ans = -1;
	while(l <= r) {
		int mid = (l + r) / 2;
		if(check(n,p,q,mid)) {
			ans = mid;
			r = mid - 1;
		}else {
			l = mid + 1;
		}
	}
	cout << ans;
	//cout << check(9);
    return 0; 
}

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