1704.Determine if String Halves Are Alike

tags: Easy,String,Counting

1704.Determine if String Halves Are Alike

題目描述

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.

範例

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.

解答

Javascript

function halvesAreAlike2(s) {
  const vowels = 'aeiouAEIOU';
  let count = 0;
  for (let i = 0; i < s.length / 2; i++) {
    if (vowels.includes(s[i])) count++;
    if (vowels.includes(s[s.length - 1 - i])) count--;
  }

  return count === 0;
}

這題用set會比較慢欸
Marsgoat Dec 1, 2022

Python

class Solution:
    def halvesAreAlike(self, s: str) -> bool:
        cnt, mid = 0, len(s) // 2
        
        for idx in range(mid):
            if s[idx] in 'aeiouAEIOU': cnt += 1
            if s[mid+idx] in 'aeiouAEIOU': cnt -= 1
                    
        return cnt == 0

Kobe Dec 1, 2022

Java

class Solution {
    public boolean halvesAreAlike(String s) {
        int cnt = 0;
        var vowels = Set.of('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U');
        for(int i = 0, j = s.length() - 1; i < j; i++, j--) {
            cnt += vowels.contains(s.charAt(i)) ? 1 : 0;
            cnt -= vowels.contains(s.charAt(j)) ? 1 : 0;
        }
        return cnt == 0;
    }
}

Java 語法越來越先進
Kobe Dec 1, 2022

TypeScript

• first submission

function halvesAreAlike(s: string): boolean {
  const vowels = 'aeiouAEIOU';
  const firstHalf = s.substring(0, s.length / 2);
  const lastHalf = s.substring(s.length / 2);

  let firstHalfVowelsCount: number = 0;
  let lastHalfVowelsCount: number = 0;

  firstHalf.split('').forEach((d) => {
    if (vowels.includes(d)) firstHalfVowelsCount++;
  });
  lastHalf.split('').forEach((d) => {
    if (vowels.includes(d)) lastHalfVowelsCount++;
  });

  return firstHalfVowelsCount === lastHalfVowelsCount;
}

• the 抄

function halvesAreAlike(s: string): boolean {
  const vowels = 'aeiouAEIOU';
  const firstHalf = s.substring(0, s.length / 2);
  const lastHalf = s.substring(s.length / 2);

  let count: number = 0;

  for (let i = 0; i < s.length / 2; i++) {
    if (vowels.includes(firstHalf[i])) count++;
    if (vowels.includes(lastHalf[i])) count--;
  }

  return count === 0;
}

sheep Dec 1, 2022

Reference

回到題目列表