List index out of range

debugcn Published at Dev

tori

I was implementing quicksort in python

#QuickSort python

def sort(array):

    leftside = []
    rightside = []
    equal = []

    pivot = array[0]

    if (len(array)>1):
        for item in array:
            if item < pivot:
                leftside.append(item)
            if item > pivot:
                rightside.append(item)
            if item == pivot:
                equal.append(item)
    else:
        print array


    print sort(leftside) + equal + sort(rightside)

array = [1,2,5,4,6,2,3]
sort(array)

I get the error "pivot = array[0] IndexError: list index out of range", I don't see anything that could cause out of index error in this code. Could you please take a look?

stanleyli

pivot = array[0] should be in if (len(array)>1):. Otherwise you may try to do it on an empty array.

Made some other quick fixes. See how this works:

#QuickSort python

def sort(array):

    leftside = []
    rightside = []
    equal = []

    if (len(array)>1):
        pivot = array[0]
        for item in array:
            if item < pivot:
                leftside.append(item)
            if item > pivot:
                rightside.append(item)
            if item == pivot:
                equal.append(item)
        return sort(leftside) + equal + sort(rightside)
    else:
        return array


array = [1,2,5,4,6,2,3]
print(sort(array))

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