Package g0801_0900.s0828_count_unique_characters_of_all_substrings_of_a_given_string

Class 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 Detail

      • Solution

        public Solution()

    • Method Detail

      • uniqueLetterString

        public int uniqueLetterString​(String s)