LeetCode in Kotlin
1358. Number of Substrings Containing All Three Characters
Medium
Given a string s consisting only of characters a, b and c.
Return the number of substrings containing at least one occurrence of all these characters a, b and c.
Example 1:
Input: s = “abcabc”
Output: 10
Explanation: The substrings containing at least one occurrence of the characters a, b and c are “_abc”, “abca”, “abcab”, “abcabc”, “bca”, “bcab”, “bcabc”, “cab”, “cabc“_ and “_abc“_ (again).
Example 2:
Input: s = “aaacb”
Output: 3
Explanation: The substrings containing at least one occurrence of the characters a, b and c are “_aaacb”, “aacb“_ and “_acb“._
Example 3:
Input: s = “abc”
Output: 1
Constraints:
3 <= s.length <= 5 x 10^4sonly consists of a, b or _c _characters.
Solution
class Solution {
fun numberOfSubstrings(s: String): Int {
val counts = IntArray(3)
var i = 0
val n = s.length
var result = 0
for (j in 0 until n) {
counts[s[j].code - 'a'.code]++
while (counts[0] > 0 && counts[1] > 0 && counts[2] > 0) {
counts[s[i++].code - 'a'.code]--
}
result += i
}
return result
}
}