README_EN.md

1704. Determine if String Halves Are Alike

中文文档

Description

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.

Example 3:

Input: s = "MerryChristmas"
Output: false

Example 4:

Input: s = "AbCdEfGh"
Output: true

 

Constraints:

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

Solutions

Python3

class Solution:
    def halvesAreAlike(self, s: str) -> bool:
        half = len(s) >> 1
        vowels = {'a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'}
        s1 = sum(1 for c in s[:half] if c in vowels)
        s2 = sum(1 for c in s[half:] if c in vowels)
        return s1 == s2

Java

class Solution {
    public boolean halvesAreAlike(String s) {
        int half = s.length() >> 1;
        Set<Character> vowels = new HashSet<>(Arrays.asList('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'));
        int s1 = 0, s2 = 0;
        for (int i = 0; i < half; ++i) {
            if (vowels.contains(s.charAt(i))) {
                ++s1;
            }
            if (vowels.contains(s.charAt(half + i))) {
                ++s2;
            }
        }
        return s1 == s2;
    }
}

...