Solution (leetcode-in-java 1.23 API)

java.lang.Object
- g1901_2000.s1915_number_of_wonderful_substrings.Solution

```
public class Solution
extends Object
```
1915 - Number of Wonderful Substrings.
Medium

A wonderful string is a string where at most one letter appears an odd number of times.
- For example, "ccjjc" and "abab" are wonderful, but "ab" is not.
Given a string word that consists of the first ten lowercase English letters ('a' through 'j'), return the number of wonderful non-empty substrings in word. If the same substring appears multiple times in word, then count each occurrence separately.

A substring is a contiguous sequence of characters in a string.

Example 1:

Input: word = “aba”

Output: 4

Explanation: The four wonderful substrings are underlined below:
- “aba” -> “a”
- “aba” -> “b”
- “aba” -> “a”
- “aba” -> “aba”
Example 2:

Input: word = “aabb”

Output: 9

Explanation: The nine wonderful substrings are underlined below:
- “aabb” -> “a”
- “aabb” -> “aa”
- “aabb” -> “aab”
- “aabb” -> “aabb”
- “aabb” -> “a”
- “aabb” -> “abb”
- “aabb” -> “b”
- “aabb” -> “bb”
- “aabb” -> “b”
Example 3:

Input: word = “he”

Output: 2

Explanation: The two wonderful substrings are underlined below:
- “he” -> “h”
- “he” -> “e”
Constraints:
- 1 <= word.length <= 10⁵
- word consists of lowercase English letters from 'a' to 'j'.

- Constructor Summary
  
  Constructors
  Constructor Description
  
  Solution()
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  long wonderfulSubstrings(String word)
  - 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

wonderfulSubstrings

public long wonderfulSubstrings(String word)