LeetCode in Kotlin
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 <= 105wordconsists of lowercase English letters from'a'to'j'.
Solution
class Solution {
fun wonderfulSubstrings(word: String): Long {
val count = IntArray(1024)
var res: Long = 0
var cur = 0
count[0] = 1
for (i in 0 until word.length) {
cur = cur xor (1 shl word[i].code - 'a'.code)
res += count[cur].toLong()
for (j in 0..9) {
res += count[cur xor (1 shl j)].toLong()
}
++count[cur]
}
return res
}
}