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.
Input: s = "book"
Output: true
Explanation: a = "bo" and b = "ok". a has 1 vowel and b has 1 vowel. Therefore, they are alike.
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.
2 <= s.length <= 1000
s.length is even.
s consists of uppercase and lowercase letters.
Solutions (Click to expand)
Have two pointers and two counters. The first pointer will traverse over the first half of the string from characters [0...n / 2) and will increment the first counter when a vowel is found.
The second pointer will traverse the second half of the string from character [n / 2...n) and will increment the second counter when a vowel is found. Once at the end of the string both of the counters will be compared.
To check if the character at a pointer is a vowel, we will have a helper function that will check if the lower case version of the character matches anyone of the lower case vowel.
1st = 0
2nd = 1
book
^ ^
1st = 1
2nd = 1
book
^ ^
Time: O(N) Where N is the length of s
Space: O(1)
determine-if-string-halves-are-alike