g0801_0900.s0828_count_unique_characters_of_all_substrings_of_a_given_string.Solution

public class Solution extends Object

828 - Count Unique Characters of All Substrings of a Given String.

Hard

Let’s define a function countUniqueChars(s) that returns the number of unique characters on s.

For example if s = "LEETCODE" then "L", "T", "C", "O", "D" are the unique characters since they appear only once in s, therefore countUniqueChars(s) = 5.

Given a string s, return the sum of countUniqueChars(t) where t is a substring of s.

Notice that some substrings can be repeated so in this case you have to count the repeated ones too.

Example 1:

Input: s = “ABC”

Output: 10

Explanation: All possible substrings are: “A”,“B”,“C”,“AB”,“BC” and “ABC”.

Evey substring is composed with only unique letters.

Sum of lengths of all substring is 1 + 1 + 1 + 2 + 2 + 3 = 10

Example 2:

Input: s = “ABA”

Output: 8

Explanation: The same as example 1, except countUniqueChars(“ABA”) = 1.

Example 3:

Input: s = “LEETCODE”

Output: 92

Constraints:

Constructor Details
- Solution
  
  public Solution()
Method Details
- uniqueLetterString
  
  public int uniqueLetterString(String s)

Class Solution

Constructor Summary