Submission #563386

#	Time	Username	Problem	Language	Result	Execution time	Memory
563386		hibiki	Watching (JOI13_watching)	C++11	100 / 100	268 ms	16016 KiB

watching

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

#define pb push_back
#define f first
#define s second

int n,p,q,dp[2005][2005];
vector<int> v;

int main()
{
    scanf("%d %d %d",&n,&p,&q);
    int lst = -1;
    for(int i = 0; i < n; i++)
    {
        int a;
        scanf("%d",&a);
        v.pb(a);
    }
    if(p + q >= n)
    {
        printf("1\n");
        return 0;
    }
    sort(v.begin(),v.end());
    int l = 1, r = 1e9 + 5;
    while(l <= r)
    {
        int mid = (l + r) / 2;
        if(l == r)
        {
            printf("%d\n",l);
            return 0;
        }
        for(int i = 0; i < n; i++)
            for(int j = 0; j <= p; j++)
                dp[i][j] = 1e9;
        for(int i = 0; i < n; i++)
        {
            int po = v[i];
            // use p
            int p_po = upper_bound(v.begin(),v.end(),po - mid) - v.begin() - 1;
            if(p_po == -1)
                dp[i][1] = 0;
            else
                for(int j = 1; j <= p; j++)
                {
                    dp[i][j] = min(dp[i][j],dp[p_po][j - 1]);
                }
            // use q
            p_po = upper_bound(v.begin(),v.end(),po - mid * 2) - v.begin() - 1;
            if(p_po == -1)
                dp[i][0] = 1;
            else
                for(int j = 0; j <= p; j++)
                {
                    dp[i][j] = min(dp[i][j],dp[p_po][j] + 1);
                }
        }
        bool chk = false;
        for(int i = 0; i <= p; i++)
            if(dp[n - 1][i] <= q)
            {
                chk = true;
                break;
            }
        if(chk)
            r = mid;
        else
            l = mid + 1;
    }
    return 0;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:14:9: warning: unused variable 'lst' [-Wunused-variable]
   14 |     int lst = -1;
      |         ^~~
watching.cpp:13:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |     scanf("%d %d %d",&n,&p,&q);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~
watching.cpp:18:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |         scanf("%d",&a);
      |         ~~~~~^~~~~~~~~

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