g0801_0900.s0828_count_unique_characters_of_all_substrings_of_a_given_string

Class Solution

java.lang.Object

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:

• 1 <= s.length <= 10⁵
• s consists of uppercase English letters only.

Constructor Summary

Constructors

Constructor and Description
Solution()

Method Summary

Modifier and Type	Method and Description
int	uniqueLetterString(String s)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Solution

public Solution()

Method Detail

uniqueLetterString

public int uniqueLetterString(String s)