Submission #219255

#	Time	Username	Problem	Language	Result	Execution time	Memory
219255		MKopchev	Watching (JOI13_watching)	C++14	100 / 100	74 ms	8576 KiB

watching

#include<bits/stdc++.h>
using namespace std;
const int nmax=2e3+42;
int n,p,q,inp[nmax];

int would_go_small[nmax],would_go_big[nmax];

int dp[nmax][nmax];

bool can(int w)
{
    for(int i=1;i<=n;i++)
    {
        would_go_small[i]=lower_bound(inp+1,inp+n+1,inp[i]+w)-inp;
        would_go_big[i]=lower_bound(inp+1,inp+n+1,inp[i]+2*w)-inp;
        //cout<<i<<" -> "<<would_go_small[i]<<" "<<would_go_big[i]<<endl;
    }

    would_go_big[n+1]=n+1;
    would_go_small[n+1]=n+1;


    for(int p_now=0;p_now<=p;p_now++)
        for(int q_now=0;q_now<=q;q_now++)
        {
            if(p_now==0&&q_now==0){dp[p_now][q_now]=1;continue;}

            int ret=0,current;
            if(p_now)
            {
            current=would_go_small[dp[p_now-1][q_now]];
            ret=max(ret,current);
            }

            if(q_now)
            {
            current=would_go_big[dp[p_now][q_now-1]];
            ret=max(ret,current);
            }

            dp[p_now][q_now]=ret;
            if(ret>n)return 1;
        }
    return 0;
}
int main()
{
    scanf("%i%i%i",&n,&p,&q);

    p=min(p,n);
    q=min(q,n);

    for(int i=1;i<=n;i++)scanf("%i",&inp[i]);
    sort(inp+1,inp+n+1);

    int ok=1e9/3+1,not_ok=0;
    while(ok-not_ok>1)
    {
        int av=(ok+not_ok)/2;
        if(can(av))ok=av;
        else not_ok=av;
    }
    printf("%i\n",ok);
    return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:48:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%i%i%i",&n,&p,&q);
     ~~~~~^~~~~~~~~~~~~~~~~~~
watching.cpp:53:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i=1;i<=n;i++)scanf("%i",&inp[i]);
                          ~~~~~^~~~~~~~~~~~~~

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