# 828. Count Unique Characters of All Substrings of a Given String LeetCode Solution

Share:

Count Unique Characters of All Substrings of a Given String Let’s define a function `countUniqueChars(s)` that returns the number of unique characters on `s`.

• For example, calling `countUniqueChars(s)` 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.

Time: O(n)
Space: O(n)

### C++

`` Will be updated Soon``

### Java

``````
Will be updated Soon``````

### Python

``````  Will be updated Soon
``````

#### Watch Tutorial

Checkout more Solutions here