LeetCode-in-Java
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
public class Solution {
public int numberOfSubstrings(String s) {
int[] counts = new int[3];
int i = 0;
int n = s.length();
int result = 0;
for (int j = 0; j < n; j++) {
counts[s.charAt(j) - 'a']++;
while (counts[0] > 0 && counts[1] > 0 && counts[2] > 0) {
counts[s.charAt(i++) - 'a']--;
}
result += i;
}
return result;
}
}