In python, how does one efficiently find the largest consecutive set of numbers in a list that are not necessarily adjacent?

Question

For instance, if I have a list

[1,4,2,3,5,4,5,6,7,8,1,3,4,5,9,10,11]

This algorithm should return [1,2,3,4,5,6,7,8,9,10,11].

To cl

Answer 1

Ok, here's yet another attempt in python:

def popper(l):
    listHolders = []
    pos = 0
    while l:
        appended = False
        item = l.pop()
        for holder in listHolders:
            if item == holder[-1][0]-1:
                appended = True
                holder.append((item, pos))
        if not appended:
            pos += 1
            listHolders.append([(item, pos)])
    longest = []
    for holder in listHolders:
        try:
            if (holder[0][0] < longest[-1][0]) and (holder[0][1] > longest[-1][1]):
                longest.extend(holder)
        except:
            pass
        if len(holder) > len(longest):
            longest = holder
    longest.reverse()
    return [x[0] for x in longest]

Sample inputs and outputs:

>>> demo = list(range(50))
>>> shuffle(demo)
>>> demo
[40, 19, 24, 5, 48, 36, 23, 43, 14, 35, 18, 21, 11, 7, 34, 16, 38, 25, 46, 27, 26, 29, 41, 8, 31, 1, 33, 2, 13, 6, 44, 22, 17,
 12, 39, 9, 49, 3, 42, 37, 30, 10, 47, 20, 4, 0, 28, 32, 45, 15]
>>> popper(demo)
[1, 2, 3, 4]
>>> demo = [1,4,2,3,5,4,5,6,7,8,1,3,4,5,9,10,11]
>>> popper(demo)
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
>>>