Submission #380777

#	Time	Username	Problem	Language	Result	Execution time	Memory
380777		mariowong	Watching (JOI13_watching)	C++14	50 / 100	1082 ms	61776 KiB

watching

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

int l,r,mid,n,p,q,a[2005],dp[2005][2005];
vector <int> v;
deque <int> dq; 
map <int,bool> m;
int main(){
	scanf("%d%d%d",&n,&p,&q);
	for (int i=1;i<=n;i++){
		scanf("%d",&a[i]);
	}
	sort(a+1,a+1+n);
	for (int i=1;i<=n;i++){
		for (int j=i;j<=n;j++){
			if (!m[a[j]-a[i]+1])
			v.push_back(a[j]-a[i]+1);
			if (!m[(a[j]-a[i]+1)/2+(a[j]-a[i]+1)%2])
			v.push_back((a[j]-a[i]+1)/2+(a[j]-a[i]+1)%2);
			m[(a[j]-a[i]+1)/2+(a[j]-a[i]+1)%2]=true;
			m[a[j]-a[i]+1]=true;
		}
	}
	sort(v.begin(),v.end());
	l=0; r=(int)v.size()-1;
	while (l < r){
		mid=(l+r)/2;
		for (int i=0;i<=min(n,q);i++){ //used how many large
			for (int j=1;j<=n;j++){
				dp[i][j]=1e9;
			}
		}
		for (int i=0;i<=min(n,q);i++){ //used how many large
			if (i > 0){
				dq.push_back(0);
				for (int j=1;j<=n;j++){
					while (!dq.empty() && a[j]-a[dq.front()+1]+1 > 2*v[mid]) dq.pop_front();
					if (dq.empty()){
						l=mid+1;
						while (!dq.empty()) dq.pop_front();
						goto out;
					}
					else
					dp[i][j]=dp[i-1][dq.front()];
					while (!dq.empty() && dp[i-1][j] <= dp[i-1][dq.back()]) dq.pop_back();
					dq.push_back(j);
				}
				while (!dq.empty()) dq.pop_back();
			}
			dq.push_back(0);
			for (int j=1;j<=n;j++){
				while (!dq.empty() && a[j]-a[dq.front()+1]+1 > v[mid]) dq.pop_front();
				if (!dq.empty())
				dp[i][j]=min(dp[i][j],dp[i][dq.front()]+1);
				while (!dq.empty() && dp[i][j] <= dp[i][dq.back()]) dq.pop_back();
				dq.push_back(j);
			}
			while (!dq.empty()) dq.pop_back();
		}
	/*	cout << l << " " << r << "\n";
		for (int i=1;i<=min(n,q);i++){ //used how many large
			for (int j=1;j<=n;j++){
				cout << dp[i][j] << " ";
			}
			cout << "\n";
		}*/
		if (dp[min(n,q)][n] <= p)
		r=mid;
		else
		l=mid+1;
		out:;
	}
	printf("%d\n",v[l]);
	return 0;
}	

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:9:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    9 |  scanf("%d%d%d",&n,&p,&q);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~
watching.cpp:11:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   11 |   scanf("%d",&a[i]);
      |   ~~~~~^~~~~~~~~~~~

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