Find Min and Max values with single recursive structure Pseudocode

Question

I'm looking for a single recursive structure algorithm to find both maximum and minimum values of an array. I've found the following pseudocode on here:

FindMaxAndMin(A, max, min)
    if (|A| == 1)
        if (max < A[1])
            max = A[1]
        if (min > A[1])
            min = A[1]
        return (min, max)
    cen = |A| /2
    l = A[:cen-1]
    h = A[cen:]
    (min, max) = FindMaxAndMin(l, min, max)
    (min, max) = FindMaxAndMin(h, min, max)
    return (min, max)

So I was wondering firstly if this counts as a single recursive structure as it all takes place under the first if. If this is a single recursive structure, I was firstly wondering what |A| represents, can't find it anywhere online, and how would it work call by call when A = (3,2,4,1) for example?

"if this counts as a single recursive structure " - you should ask whoever give you the assignment... — Alexei Levenkov
– Alexei Levenkov, Commented Dec 12, 2018 at 0:11
@AlexeiLevenkov it is an online task, I've googled the meaning and I cannot find it. I'm assuming it means something quite trivial though perhaps I've never heard it been called that. — bemzoo
– bemzoo, Commented Dec 12, 2018 at 1:39
@bemzoo It's not a commonly used term with a fixed meaning. Would you mind providing a link to the original problem? — yeputons
– yeputons, Commented Dec 12, 2018 at 5:39

Naor Tedgi · Accepted Answer · 2018-12-12 10:51:04Z

1

|A| is just the length of the array

you can debug and follow the steps here

(becuse i use js i couldnt return 2 values thats way i changes it to an array

keep in mind that minMax[0] = min

and minMax[1] = max

i initilized minMax[0] (min) with MAX_SAFE_INTEGER

and minMax[0] (max) with MIN_SAFE_INTEGER)

const FindMaxAndMin = (A, minMax)=>{
    if (A.length === 1){
        if (minMax[1] < A[0])
            minMax[1] = A[0]
        if (minMax[0] > A[0])
            minMax[0] = A[0]
        return minMax
    }
    let cen = A.length /2
    let l = A.slice(0,cen)
    let h = A.slice(cen,A.length)
    minMax = FindMaxAndMin(l, minMax)
    minMax = FindMaxAndMin(h, minMax)
    return minMax
  }
  
  console.log(FindMaxAndMin([3,4,1,2],[Number.MAX_SAFE_INTEGER , Number.MIN_SAFE_INTEGER]))

edited Dec 12, 2018 at 10:51

answered Dec 12, 2018 at 10:45

Naor Tedgi

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