Submission #68372

#	Time	Username	Problem	Language	Result	Execution time	Memory
68372		Kerim	Watching (JOI13_watching)	C++17	100 / 100	539 ms	16928 KiB

watching

#include "bits/stdc++.h"
#define MAXN 100009
#define INF 1000000007
#define mp(x,y) make_pair(x,y)
#define all(v) v.begin(),v.end()
#define pb(x) push_back(x)
#define wr cout<<"----------------"<<endl;
#define ppb() pop_back()
#define tr(ii,c) for(__typeof((c).begin()) ii=(c).begin();ii!=(c).end();ii++)
#define ff first
#define ss second
#define my_little_dodge 46
#define debug(x)  cerr<< #x <<" = "<< x<<endl;
using namespace std;

typedef long long ll;
typedef pair<int,int> PII;
template<class T>bool umin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool umax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
int n,X,Y;
int arr[MAXN],a[MAXN],b[MAXN];
const int N=2004;
int dp[N][N];
int rec(int x,int y){
	if(x>n)
		return 0;
	int &ret=dp[x][y];
	if(~ret)
		return ret;
	ret=rec(b[x],y)+1;
	if(y)
		umin(ret,rec(a[x],y-1));
	return ret;	
}
bool ok(int w){
	int p=n;
	for(int i=n;i>=1;i--){
		while(arr[p]-arr[i]>=w)
			p--;
		a[i]=p+1;	
	}p=n;
	for(int i=n;i>=1;i--){
		while(arr[p]-arr[i]>=2*w)
			p--;
		b[i]=p+1;	
	}	
	memset(dp,-1,sizeof dp);
	return (rec(1,min(n,X))<=Y);
}
int main(){
    //~ freopen("file.in", "r", stdin); 
    scanf("%d%d%d",&n,&X,&Y);
    for(int i=1;i<=n;i++)
		scanf("%d",arr+i);
	sort(arr+1,arr+n+1);
	int st=1,en=INF;
	while(st+1<en){
		int mid=(st+en)>>1;
		if(ok(mid))
			en=mid;
		else
			st=mid;
	}
	if(ok(st))
		en=st;
	printf("%d\n",en);	
	return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:52:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d",&n,&X,&Y);
     ~~~~~^~~~~~~~~~~~~~~~~~~
watching.cpp:54:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",arr+i);
   ~~~~~^~~~~~~~~~~~

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