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 10^4s only consists of a, b or c characters.class Solution { public int numberOfSubstrings(String s) { int count[] = {0, 0, 0}, res = 0 , i = 0, n = s.length(); for (int j = 0; j < n; ++j) { ++count[s.charAt(j) - ‘a‘]; while (count[0] > 0 && count[1] > 0 && count[2] > 0) --count[s.charAt(i++) - ‘a‘]; res += i; } return res; } }
sliding window
class Solution { public int numberOfSubstrings(String s) { int[] count = new int[3]; int res = 0; for(int lo = -1, hi = 0; hi < s.length(); hi++){ count[s.charAt(hi) - ‘a‘]++; while(count[0] > 0 && count[1] > 0 && count[2] > 0){ res += s.length() - hi; --count[s.charAt(++lo) - ‘a‘]; } } return res; } }
1358. Number of Substrings Containing All Three Characters
原文：https://www.cnblogs.com/wentiliangkaihua/p/12360775.html