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Solution: Total Appeal of a String

Understand how to solve the total appeal of a string problem by leveraging hash maps to track the last occurrence of each character. This lesson guides you through calculating the contribution of characters to the appeal using efficient substring counting methods, optimizing the solution to run in linear time with constant space.

Statement

Given a string s, return its total appeal, which is calculated by summing the appeals of all its substringsA substring is a contiguous sequence of characters within a string..

The appeal of a string is defined as the count of unique characters present in that string.

For instance, the appeal of “xyzxz” is 3 ...