You are given a string chatMessage. Your task is to count the number of substrings of exactly length 3 that contain at least one vowel (a, e, i, o, u, or their uppercase counterparts). Return this number as an integer.
Examples:
For chatMessage = "CodeSignal", the output should be solution(chatMessage) = 8.
The substrings of length 3 are: Cod, ode, deS, eSi, Sig, ign, gna, and nal. All these substrings contain at least one vowel. Thus, the answer is 8.
For chatMessage = "StrEngThen", the output should be solution(chatMessage) = 5.
The substrings of length 3 are: Str, trE, rEn, Eng, ngT, gTh, The, and hen. The substrings that contain at least one vowel are trE, rEn, Eng, The, and hen. Thus, the answer is 5.
Input/Output
[execution time limit] 4 seconds (py3)[memory limit] 1 GB[input] string chatMessage
A sequence of characters representing a chat message.[output] integer
The number of substrings of exactly length 3 where at least one character is a case-insensitive vowel.
This is a fixed-size sliding window problem: scan every consecutive substring of length 3 and count those that contain at least one vowel, case-insensitively. Because the window length is constant, a simple O(n) pass is enough, optionally maintaining the number of vowels currently in the window. The examples show that strings like "CodeSignal" produce 8, while "StrEngThen" produce 5.
