Submission #870145

#	Time	Username	Problem	Language	Result	Execution time	Memory
870145		Eliorita	Watching (JOI13_watching)	C++14	100 / 100	295 ms	32088 KiB

watching

#include<bits/stdc++.h>
#define int long long
#define pb push_back
#define x first
#define y second
#define getbit(u,i) ((u>>i)&1)
#define all(x) x.begin(),x.end()
#define N 200001
using namespace std;
typedef pair<int,int> ii;
typedef pair<double,double> dd;
int n,a,b,A[N],dp[2001][2001],ans,l=1,r=1e9+8;
bool check(int x)
{
    int mn=LLONG_MAX;
    memset(dp,0x3f,sizeof(dp));
    dp[0][0]=0;
    for(int i=1;i<=n;i++)
    {
        int l=1,r=1;
        while(l<i&&A[i]>=x+A[l]) l++;
        for(int j=0;j<=b;j++) dp[i][j]=dp[l-1][j]+1;
        while(r<i&&A[i]>=2*x+A[r]) r++;
        for(int j=0;j<=b;j++) dp[i][j+1]=min(dp[i][j+1],dp[r-1][j]);
    }
    for(int i=0;i<=b;i++) mn=min(mn,dp[n][i]);
    return mn<=a;
}
signed main()
{
    if(fopen("paint.inp","r"))
    {
        freopen("paint.inp","r",stdin);
        freopen("paint.out","w",stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin>>n>>a>>b;
    if(n<=a+b) {cout<<1; return 0;}
    for(int i=1;i<=n;i++) cin>>A[i];
    sort(A+1,A+n+1);
    while(l<=r)
    {
        int m=(l+r)/2;
        if(check(m))
        {
            ans=m;
            r=m-1;
        }
        else l=m+1;
    }
    cout<<ans;
}

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:33:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |         freopen("paint.inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
watching.cpp:34:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |         freopen("paint.out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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