Watch 10 video solutions for Number of Equal Count Substrings, a medium level problem involving String, Counting, Prefix Sum. This walkthrough by NeetCode has 657,697 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
You are given a 0-indexed string s consisting of only lowercase English letters, and an integer count. A substring of s is said to be an equal count substring if, for each unique letter in the substring, it appears exactly count times in the substring.
Return the number of equal count substrings in s.
A substring is a contiguous non-empty sequence of characters within a string.
Example 1:
Input: s = "aaabcbbcc", count = 3 Output: 3 Explanation: The substring that starts at index 0 and ends at index 2 is "aaa". The letter 'a' in the substring appears exactly 3 times. The substring that starts at index 3 and ends at index 8 is "bcbbcc". The letters 'b' and 'c' in the substring appear exactly 3 times. The substring that starts at index 0 and ends at index 8 is "aaabcbbcc". The letters 'a', 'b', and 'c' in the substring appear exactly 3 times.
Example 2:
Input: s = "abcd", count = 2 Output: 0 Explanation: The number of times each letter appears in s is less than count. Therefore, no substrings in s are equal count substrings, so return 0.
Example 3:
Input: s = "a", count = 5 Output: 0 Explanation: The number of times each letter appears in s is less than count. Therefore, no substrings in s are equal count substrings, so return 0
Constraints:
1 <= s.length <= 3 * 1041 <= count <= 3 * 104s consists only of lowercase English letters.