Permutation in String

Write `contains_permutation(pattern, text)` returning `True` when any permutation of `pattern` appears as a contiguous substring of `text`. contains_permutation("ab", "eidbaooo") -> True ("ba") contains_permutation("ab", "eidboaoo") -> False The window is a fixed width, so this is simpler than it looks: slide it one character at a time, adding on the right and removing on the left. Comparing whole count maps at each step is O(26n); maintaining a count of how many characters currently match is O(n).