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pythonlistalgorithmtime-complexityminmax

Maximum number irrespective of sign from positive and negative numbers in a list

I want to find the maximum number from a list that has both positive, negative number and irrespective of sign. For example:

arr = [2,3,-6,5]
## output: -6

arr = [2,3,6,-5]
## output: 6

I've the following code which is working:

def max_number(l):
    abs_maxval = max(l,key=abs)
    maxval = max(l)
    minval = min(l)
    if maxval == abs_maxval:
        return maxval
    else:
        return minval

Though this is working and the time complexity is O(N), I'm wondering if there is a way to find the number faster or optimize the code? From my understanding I'm scanning the list 3 times which might be slower for a large list and for my problem, I'm going through hundreds of thousands large lists. Any suggestion will be helpful. Thanks!

Solution

  • You should just be able to

    max(arr, key=abs)