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LeetCode 解题报告(339) -- 1704. Determine if String Halves Are Alike

Problem

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:

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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:

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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:

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Input: s = "MerryChristmas"
Output: false

Example 4:

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Input: s = "AbCdEfGh"
Output: true

Constraints:

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

Analysis

   题目给出一个字符串,从中间对半切开,要求我们判断前半部分和后半部分中包含的元音字母个数是否相同。

   因为是前后两半对比,所以遍历一半就可以了,每个字符都判断下是否元音,前后两部分各自统计一下元音出现的次数,最后看看两者是否相等即可。


Solution

   注意大小写的问题,


Code

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class Solution {
public:
bool halvesAreAlike(string s) {
int size = s.size ();
int num1 = 0, num2 = 0;
for (int i = 0; i < size / 2; i++) {
if (isVowel (s [i])) {
num1++;
}
if (isVowel (s [size - 1 - i])) {
num2++;
}
}
//cout << num1 << " " << num2 << endl;
return num1 == num2;
}
private:
bool isVowel(char c) {
if (c == 'A' || c == 'E' || c == 'I' || c == 'O' || c == 'U' ||
c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u') {
return true;
}
return false;
}
};

Summary

   这是一道非常简单的字符串遍历题目,没什么难点。这道题目的分享到这里,感谢你的支持!

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