A wonderful string is a string where at most one letter appears an oddnumber 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'
.