Leetcode 1880. Check if Word Equals Summation of Two Words

Map each letter 'a'..'j' to digits 0..9, form each word's numerical value by concatenating those digits and parsing as an integer, and check whether firstWord_value + secondWord_value equals targetWord_value. Inputs use only letters 'a'–'j' with length ≤ 8, so the resulting numbers fit comfortably in standard integer types.