[LeetCode] 344. Reverse String 翻轉字符串

 

Write a function that reverses a string. The input string is given as an array of characters char[].

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

You may assume all the characters consist of printable ascii characters.

 

Example 1:

Input: ["h","e","l","l","o"]
Output: ["o","l","l","e","h"] 

Example 2:

Input: ["H","a","n","n","a","h"]
Output: ["h","a","n","n","a","H"]

 

這道題沒什么難度，直接從兩頭往中間走，同時交換兩邊的字符即可，參見代碼如下：

 

解法一：

class Solution {
public:
    void reverseString(vector<char>& s) {
        int left = 0, right = (int)s.size() - 1;
        while (left < right) {
            char t = s[left];
            s[left++] = s[right];
            s[right--] = t;
        }
    }
};

 

我們也可以用 swap 函數來幫助我們翻轉：

 

解法二：

class Solution {
public:
    void reverseString(vector<char>& s) {
        int left = 0, right = (int)s.size() - 1;
        while (left < right) {
            swap(s[left++], s[right--]);
        }
    }
};

 

Github 同步地址：

https://github.com/grandyang/leetcode/issues/344

 

類似題目：

Reverse Words in a String II

Reverse Words in a String

Reverse Vowels of a String 

Reverse String II

 

參考資料：

https://leetcode.com/problems/reverse-string/

https://leetcode.com/problems/reverse-string/discuss/80935/Simple-C%2B%2B-solution

https://leetcode.com/problems/reverse-string/discuss/80937/JAVA-Simple-and-Clean-with-Explanations-6-Solutions

 

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