344. Reverse String

1.问题描述

Write a function that takes a string as input and returns the string reversed.
Example:
Given s = “hello”, return “olleh”.
来自 https://leetcode.com/problems/reverse-string/description/

2.题目分析

对字符串经行反转，可以调用string类的reverse成员函数，也可以自己写。

3.c++代码

//我的c++代码：(beats 97%)
string reverseString(string& s)
{
    for (int i = 0, j= s.length()-1; i < j; i++,j--)
    {
        char c = s[j];
        s[j] = s[i];
        s[i] = c;
    }
    return s;
}

4.string类的reverse函数

//algorithm中的定义
template <class BidirectionalIterator>  
  void reverse (BidirectionalIterator first, BidirectionalIterator last)  
{  
  while ((first!=last)&&(first!=--last)) {  
    std::iter_swap (first,last);  
    ++first;  
  }  
}  

#include<iostream>  
#include<string>  
#include<cstring>  
#include<algorithm>  
using namespace std;
int main()
{
    string a;
    while (cin >> a)
    {
        string b;
        reverse(a.begin(), a.end());
        cout << a << endl;
        b = a;
        cout << b << endl;
    }
    return 0;
}