Submission #197498

#	Time	Username	Problem	Language	Result	Execution time	Memory
197498		handlename	Watching (JOI13_watching)	C++17	100 / 100	299 ms	16376 KiB

watching

#include <bits/stdc++.h>
using namespace std;
int arr[2001],w,n,memo[2005][2005];
int memo2[2005][2];
int dp(int index,int p){
    if (index<p || index<0) return 0;
    if (index==0) return 1;
    if (memo[index][p]!=-1) return memo[index][p];
    int x,y;
    if (memo2[index][0]!=-1){
        x=memo2[index][0];
        y=memo2[index][1];
    }
    else {
        memo2[index][0]=x=upper_bound(arr,arr+n,arr[index]-2*w)-1-arr;
        memo2[index][1]=y=upper_bound(arr,arr+n,arr[index]-w)-1-arr;
    }
    if (p==0) return memo[index][p]=dp(x,p)+1;
    return memo[index][p]=min(dp(x,p)+1,dp(y,p-1));
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
	int p,q;
    cin>>n>>p>>q;
    for (int i=0;i<n;i++) cin>>arr[i];
    if (p+q>=n){
        cout<<1;
        return 0;
    }
    memset(memo,-1,sizeof(memo));
    sort(arr,arr+n);
    int mini=0,maxi=1000000000;
    while (mini+1<maxi){
        w=(mini+maxi)/2;
        if (dp(n-1,p)>q) mini=w;
        else maxi=w;
        memset(memo,-1,sizeof(memo));
        memset(memo2,-1,sizeof(memo2));
    }
    cout<<maxi;
}

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