substrings-of-size-three-with-distinct-characters_1876.py

# A string is good if there are no repeated characters.

# Given a string s​​​​​, return the number of good substrings of length three in s​​​​​​.

# Note that if there are multiple occurrences of the same substring, every occurrence should be counted.

# A substring is a contiguous sequence of characters in a string.

# Example 1:

# Input: s = "xyzzaz"
# Output: 1
# Explanation: There are 4 substrings of size 3: "xyz", "yzz", "zza", and "zaz".
# The only good substring of length 3 is "xyz".
# Example 2:

# Input: s = "aababcabc"
# Output: 4
# Explanation: There are 7 substrings of size 3: "aab", "aba", "bab", "abc", "bca", "cab", and "abc".
# The good substrings are "abc", "bca", "cab", and "abc".


# ---------------------------------------Runtime 44 ms Beats 59.82% Memory 16.4 MB Beats 13.67%---------------------------------------


# My solution
# Time complexity O(n)
class Solution:
    def countGoodSubstrings(self, s: str) -> int:
        k: int = 3
        res: int = 0
        for i in range(len(s) - k + 1):
            if len(set(s[i : i + k])) >= k:
                res += 1
        return res


# ---------------------------------------Runtime 39 ms Beats 75.88% Memory 16.3 MB Beats 46.15%---------------------------------------


# My solution 2
# Time complexity O(n)
class Solution:
    def countGoodSubstrings(self, s: str) -> int:
        k: int = 3
        res: int = 0
        for i in range(len(s) - k + 1):
            sub_array = s[i : i + k]
            if (
                sub_array[0] != sub_array[1]
                and sub_array[0] != sub_array[-1]
                and sub_array[-1] != sub_array[1]
            ):
                res += 1
        return res