2063. Vowels of All Substrings

Given a string word, return the sum of the number of vowels ('a', 'e', 'i', 'o', and 'u') in every substring of word. A substring is a contiguous (non-empty) sequence of characters within a string. Note: Due to the large constraints, the answer may not fit in a signed 32-bit integer. Please be careful during the calculations. Example 1: Input: word = "aba" Output: 6 Explanation: All possible