leetcode344

public class Solution {
    public string ReverseString(string s) {
        var list = s.Reverse();
            StringBuilder sb = new StringBuilder();

            foreach (var c in list)
            {
                sb.Append(c);
            }


            //Console.WriteLine(sb.ToString());
            return sb.ToString();
    }
}

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

下面是使用C++的解决方案，不实用api：

class Solution {
public:
    string reverseString(string s) {
        string temp = "";
        for (int i = s.length() - 1; i >= 0; i--)
        {
            temp += s[i];
        }
        return temp;
    }
};

这道题目有所变化，原来的要求是返回string，现在的要求是不返回任何值，而是在原来的字符串上直接修改。 下面使用python实现新的要求：

class Solution:
    def reverseString(self, s: List[str]) -> None:
        """
        Do not return anything, modify s in-place instead.
        """
        n = len(s)
        i,j = 0,n-1
        while i < j:
            s[j],s[i] = s[i],s[j]
            i += 1
            j -= 1