Kata: https://www.codewars.com/kata/range-extraction/python
A format for expressing an ordered list of integers is to use a comma separated list of either
- individual integers
- or a range of integers denoted by the starting integer separated from the end integer in the range by a dash, '-'. The range includes all integers in the interval including both endpoints. It is not considered a range unless it spans at least 3 numbers. For example ("12, 13, 15-17")
Complete the solution so that it takes a list of integers in increasing order and returns a correctly formatted string in the range format.
Example:
solution([-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20]) # returns "-6,-3-1,3-5,7-11,14,15,17-20"
Courtesy of rosettacode.org
My Code
def solution(lst):
res = []
if lst:
tmp, i, ln = lst[0], 0, len(lst)
while i < ln:
tmp, j = lst[i], i
while j < ln - 1 and lst[j+1] == lst[j]+1:
j += 1
if j - i > 1:
tmp = str(lst[i]) + "-" + str(lst[j])
i = j+1
else:
i = (j if j > i else i+1)
res.append(tmp)
return ",".join(str(x) for x in res)