To find the greatest number in the array without max function

Why do you want to do it without the max() function when you can use it?

reduce(
  rule!getMaxNumber(accumulator: _, item: _),
  0,
  ri!array
)

We can use reduce function

Create a rule which will compare the current item and accumulator and return the max number and use that rule as predicate in reduce fucntion

Or use the sort function:

a!localVariables(
  local!list:{5,4,7,9,2,5,0},
  sort(local!list)[length(local!list)]
)

This might be helpful.

a!localVariables(
  local!listOfNumber: { 67, 80, 100, 102, 150 },
  a!forEach(
    items: local!listOfNumber,
    expression: a!localVariables(
      local!item: fv!item,
      local!updatedList: remove(local!listOfNumber, fv!index),
      if(
        count(
          wherecontains(
            true,
            a!forEach(
              items: local!updatedList,
              expression: local!item > fv!item
            )
          )
        ) = count(local!updatedList),
        fv!item,
        {}
      )
    )
  )
)

Here is an O(n) approach implemented like C, employing a temporary variable to store the current maximum (rule input ). In this implementation, a recursive approach has been utilized. If you have any questions or need further clarification, feel free to ask.

  if(
    ri!currentIndex > length(ri!arr),
    ri!currentMax,
    rule!maxNum(
      arr: ri!arr,
      currentMax: if(
        ri!currentMax > ri!arr[ri!currentIndex],
        ri!currentMax,
        ri!arr[ri!currentIndex]
      ),
      currentIndex: ri!currentIndex + 1
    )
  )


/*arr: array in which we needs to find max num*/
/*currentMax: first element of array*/
/*current index: first index of array (1 in case of appian)*/

result-> 

Hi [mention:7cd3b09aef6f4206aa547fd04a01861e:e9ed411860ed4f2ba0265705b8793d05] ,

Below one might be helpful.

a!localVariables(
  local!list: { 67, 80, 100, 102, 150 },
  local!map: a!forEach(
    items: local!list,
    expression: a!map(number: fv!item)
  ),
  index(
    index(
      index(
        todatasubset(
          arrayToPage: local!map,
          pagingConfiguration: a!pagingInfo(
            startIndex: 1,
            batchSize: length(local!list),
            sort: a!sortInfo(field: "number", ascending: false)
          )
        ),
        "data",
        {}
      ),
      "number",
      {}
    ),
    1,
    {}
  )
)