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
双指针遍历计数
class Solution {
public:
bool halvesAreAlike(string s) {
int n = s.size();
int a = 0, b = n / 2, va = 0, vb = 0;
while (a < n / 2) {
switch (s[a]) {
case 'a':
case 'e':
case 'i':
case 'o':
case 'u':
case 'A':
case 'E':
case 'I':
case 'O':
case 'U':
va++;
break;
default:
break;
}
a++;
}
while (b < n) {
switch (s[b]) {
case 'a':
case 'e':
case 'i':
case 'o':
case 'u':
case 'A':
case 'E':
case 'I':
case 'O':
case 'U':
vb++;
break;
default:
break;
}
b++;
}
return va == vb;
}
};
