How hard is LeetCode 2947. Count Beautiful Substrings I?

LeetCode 2947. Count Beautiful Substrings I is rated Medium on LeetCode.

What is the time complexity of LeetCode 2947. Count Beautiful Substrings I?

The Python solution on this page runs in O(n).

What is the space complexity of LeetCode 2947. Count Beautiful Substrings I?

The Python solution on this page uses O(n) auxiliary space.

What topics does LeetCode 2947. Count Beautiful Substrings I cover?

LeetCode 2947. Count Beautiful Substrings I is tagged Hash Table, Math, String, Enumeration, Number Theory and Prefix Sum on LeetCode.

Count Beautiful Substrings I — LeetCode 2947 Python Solution

MediumHash TableMathStringEnumerationNumber TheoryPrefix Sum

Problem: #2947
Pattern: Prefix Sum
Reading time: 3 min
Source: leetcode.com

The problem

You are given a string s and a positive integer k. Let vowels and consonants be the number of vowels and consonants in a string.

Example

Input: s = "baeyh", k = 2
Output: 2
Explanation: There are 2 beautiful substrings in the given string.

Python solution

Python

class Solution:
    def beautifulSubstrings(self, s: str, k: int) -> int:
        n = len(s)
        vs = set("aeiou")
        ans = 0
        for i in range(n):
            vowels = 0
            for j in range(i, n):
                vowels += s[j] in vs
                consonants = j - i + 1 - vowels
                if vowels == consonants and vowels * consonants % k == 0:
                    ans += 1
        return ans

Complexity

Measure	Complexity
Time	O(n)
Space	O(n) auxiliary

Pattern: Prefix Sum

Precompute running totals once so any range query becomes a single subtraction. LeetCode 2947. Count Beautiful Substrings I is filed here because LeetCode tags it Prefix Sum, which is the vocabulary this hub collects.

The prefix sum guide has the Python template for the pattern and the 157 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 2947. Count Beautiful Substrings I?: LeetCode 2947. Count Beautiful Substrings I is rated Medium on LeetCode.
What is the time complexity of LeetCode 2947. Count Beautiful Substrings I?: The Python solution on this page runs in O(n).
What is the space complexity of LeetCode 2947. Count Beautiful Substrings I?: The Python solution on this page uses O(n) auxiliary space.
What topics does LeetCode 2947. Count Beautiful Substrings I cover?: LeetCode 2947. Count Beautiful Substrings I is tagged Hash Table, Math, String, Enumeration, Number Theory and Prefix Sum on LeetCode.