LeetCode 1358. Number of Substrings Containing All Three Characters in F#

URL Number of Substrings Containing All Three Characters - LeetCode Code https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202503/number_of_substrings_containing_all_three_characters/main.fsx let numberOfSubstrings (s: stri...