344. Reverse String(easy)

Easy

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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"]

 

使用库函数reverse:

C++:

/*
 * @Autor: SourDumplings
 * @Date: 2019-09-11 08:53:06
 * @Link: https://github.com/SourDumplings/
 * @Email: changzheng300@foxmail.com
 * @Description: https://leetcode.com/problems/reverse-string/
 */

class Solution
{
public:
    void reverseString(vector<char> &s)
    {
        reverse(s.begin(), s.end());
    }
};

 循环交换法:

Java:

/*
 * @Autor: SourDumplings
 * @Date: 2019-09-11 08:54:47
 * @Link: https://github.com/SourDumplings/
 * @Email: changzheng300@foxmail.com
 * @Description: https://leetcode.com/problems/reverse-string/
 */

class Solution
{
    public void reverseString(char[] s)
    {
        int l = s.length;
        for (int i = 0; i < l / 2; i++)
        {
            char temp = s[i];
            s[i] = s[l - 1 - i];
            s[l - i - 1] = temp;
        }
    }
}