Submission #765837

#	Time	Username	Problem	Language	Result	Execution time	Memory
765837		yusuf12360	Watching (JOI13_watching)	C++14	100 / 100	539 ms	15340 KiB

watching

#include<bits/stdc++.h>
using namespace std;
vector<int> a;
int n, p, q;
bool can(int w) {
	vector<vector<int>> dp(n, vector<int>(p+1));
	vector<int> small_dist(n), big_dist(n);
	int SMALL=0, BIG=0;
	for(int i=0; i<n; i++) {
		if(a[0]>=a[i]-w+1) small_dist[i]=-1;
		else {
			while(a[SMALL]<a[i]-w+1) SMALL++;
			small_dist[i]=--SMALL;
		}
		if(a[0]>=a[i]-2*w+1) big_dist[i]=-1;
		else {
			while(a[BIG]<a[i]-2*w+1) BIG++;
			big_dist[i]=--BIG;
		}
	}
	for(auto &p : dp) for(int &pp : p) pp=1e4;
	dp[0][0]=1;
	for(int i=1; i<=p; i++) dp[0][1]=0;
	for(int i=1; i<n; i++) {
		for(int j=0; j<=p; j++) {
			SMALL=small_dist[i], BIG=big_dist[i];
			if(j) {
				if(SMALL==-1) dp[i][j]=0;
				else dp[i][j]=min(dp[i][j], dp[SMALL][j-1]);
			}
			if(BIG==-1) dp[i][j]=min(dp[i][j], 1);
			else dp[i][j]=min(dp[i][j], dp[BIG][j]+1);
		}
	}
	for(int i=0; i<=p; i++) {if(dp[n-1][i]<=q) return 1;}
	return 0;
}
int main() {
	ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	cin >> n >> p >> q;
	a.resize(n);
	for(int &p : a) cin >> p;
	if(p+q>=n) {cout << "1\n"; return 0;}
	sort(a.begin(), a.end());
	int l=1, r=1e9, w=1e9;
	while(l<=r) {
		int mid=(l+r)/2;
		if(can(mid)) w=mid, r=mid-1;
		else l=mid+1;
	}
	cout << w << '\n';
	return 0;
}

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