Re: [OT] Lower and upper median of 4

[Andrei Alexandrescu via Digitalmars-d]

On 11/26/2016 03:19 PM, Timon Gehr wrote:

The following code (which I found using a quick brute-force search) uses
at most 4 comparisons.


int median(bool leanRight)(int[4] a){
    static if(leanRight){
        return
a[a[0]<a[1]?a[2]<a[3]?a[1]<a[3]?a[1]<a[2]?2:1:a[0]<a[3]?3:0:a[1]<a[2]?a[1]<a[3]?3:1:a[0]<a[2]?2:0:a[2]<a[3]?a[0]<a[3]?a[0]<a[2]?2:0:a[1]<a[3]?3:1:a[0]<a[2]?a[0]<a[3]?3:0:a[1]<a[2]?2:1];

    }else{
        return
a[a[0]<a[1]?a[2]<a[3]?a[0]<a[2]?a[1]<a[2]?1:2:a[0]<a[3]?0:3:a[0]<a[3]?a[1]<a[3]?1:3:a[0]<a[2]?0:2:a[2]<a[3]?a[1]<a[2]?a[0]<a[2]?0:2:a[1]<a[3]?1:3:a[1]<a[3]?a[0]<a[3]?0:3:a[1]<a[2]?1:2];

    }
}

Thanks! Sorry, I forgot to mention partitioning around the lower/upper 
median is also needed. It seems that changes the tradeoff space. -- Andrei