broken-sequence

Broken sequence

You receive some random elements as a space-delimited string. Check if the elements are part of an ascending sequence of integers starting with 1, with an increment of 1 (e.g. 1, 2, 3, 4).

Return:

• 0 if the elements can form such a sequence, and no number is missing ("not broken", e.g. "1 2 4 3")
• 1 if there are any non-numeric elements in the input ("invalid", e.g. "1 2 a")
• n if the elements are part of such a sequence, but some numbers are missing, and n is the lowest of them ("broken", e.g. "1 2 4" or "1 5")

Examples

"1 2 3 4"  ==>  return 0, because the sequence is complete

"1 2 4 3"  ==>  return 0, because the sequence is complete (order doesn't matter)

"2 1 3 a"  ==>  return 1, because it contains a non numerical character

"1 3 2 5"  ==>  return 4, because 4 is missing from the sequence

"1 5"      ==>  return 2, because the sequence is missing 2, 3, 4 and 2 is the lowest