Submission #51477

#	Time	Username	Problem	Language	Result	Execution time	Memory
51477		mergesort	Watching (JOI13_watching)	C++14	100 / 100	282 ms	16512 KiB

watching

#include<bits/stdc++.h>
using namespace std;
int a[2005],n,p,q;
int len1[2005],len2[2005],dp[2005][2005];
bool check(int w)
{
    for(int i=1;i<=n;++i){
        len1[i]=len2[i]=i;
        for(int j=i+1;j<=n;++j){
            if(a[i]+w-1>=a[j])len1[i]=j;
            if(a[i]+2*w-1>=a[j])len2[i]=j;
        }
    }
    len1[n+1]=len2[n+1]=n;
    memset(dp,-1,sizeof dp);
    dp[0][0]=0;
    for(int i=0;i<=p;++i){
        for(int j=0;j<=q;++j){
            if(i==0 && j==0)continue;
            if(i==0 && j){
                dp[i][j]=max(dp[i][j],len2[dp[i][j-1]+1]);
                continue;
            }
            else if(i && j==0){
                dp[i][j]=max(dp[i][j],len1[dp[i-1][j]+1]);
                continue;
            }
            int pos1=dp[i-1][j],pos2=dp[i][j-1];
            if(pos1>=n || pos2>=n){
                dp[i][j]=n;
                return true;
            }
            pos1++;
            pos2++;
            dp[i][j]=max(len1[pos1],len2[pos2]);
            if(dp[i][j]>=n)return true;
        }
    }
    if(dp[p][q]>=n)return true;
    else return false;
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin>>n>>p>>q;
    for(int i=1 ;i<=n;++i)cin>>a[i];
    sort(a+1,a+1+n);
    if(p+q>=n){
        cout<<"1";
        return 0;
    }
    int l=0,r=1e9;
    while(l+1<r){
        int mid=(l+r)/2;
        if(check(mid))r=mid;
        else l=mid;
    }
    //cout<<check(4)<<"\n****"<<endl;
    int ans=1e9;
    if(check(r))ans=min(ans,r);
    if(check(l))ans=min(ans,l);
    cout<<ans;
}

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