Java Coding Problems

1. Counting duplicate characters

The solution to counting the characters in a string (including special characters such as #, $, and %) implies taking each character and comparing them with the rest. During the comparison, the counting state is maintained via a numeric counter that's increased by one each time the current character is found.

There are two solutions to this problem.

The first solution iterates the string characters and uses Map to store the characters as keys and the number of occurrences as values. If the current character was never added to Map, then add it as (character, 1). If the current character exists in Map, then simply increase its occurrences by 1, for example, (character, occurrences+1). This is shown in the following ...