public class Solution
extends Object
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 10^4`
* `s` only consists of _a_, _b_ or _c _characters.