1704. Determine if String Halves Are Alike

Problem Link

Description

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You are given a string s of even length. Split this string into two halves of equal lengths, and let a be the first half and b be the second half.

Two strings are alike if they have the same number of vowels ('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'). Notice that s contains uppercase and lowercase letters.

Return true if a and b are alike. Otherwise, return false.

 

Example 1:

Input: s = "book"
Output: true
Explanation: a = "bo" and b = "ok". a has 1 vowel and b has 1 vowel. Therefore, they are alike.

Example 2:

Input: s = "textbook"
Output: false
Explanation: a = "text" and b = "book". a has 1 vowel whereas b has 2. Therefore, they are not alike.
Notice that the vowel o is counted twice.

 

Constraints:

• 2 <= s.length <= 1000
• s.length is even.
• s consists of uppercase and lowercase letters.

Solution

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Python3

class Solution:
    def halvesAreAlike(self, s: str) -> bool:
        N = len(s)
        first = last = 0
 
        for i, x in enumerate(s):
            if x in 'aeiouAEIOU':
                if i < N // 2:
                    first += 1
                else:
                    last += 1
                    if last > first: return False
        
        return first == last