Update summarize_ranges.py (#912)

algorithms/arrays/summarize_ranges.py

@@ -6,22 +6,20 @@
 """
 
 
-def summarize_ranges(array):
- """
- :type array: List[int]
- :rtype: List[]
- """
+from typing import List
+
+def summarize_ranges(array: List[int]) -> List[str]:
  res = []
  if len(array) == 1:
  return [str(array[0])]
- i = 0
- while i < len(array):
- num = array[i]
- while i + 1 < len(array) and array[i + 1] - array[i] == 1:
- i += 1
- if array[i] != num:
- res.append((num, array[i]))
+ it = iter(array)
+ start = end = next(it)
+ for num in it:
+ if num - end == 1:
+ end = num
  else:
- res.append((num, num))
- i += 1
- return res
+ res.append((start, end) if start != end else (start,))
+ start = end = num
+ res.append((start, end) if start != end else (start,))
+ return [f"{r[0]}-{r[1]}" if len(r) > 1 else str(r[0]) for r in res]
+