344. Reverse String

Write a function that takes a string as input and returns the string reversed.

Example:

Given s = "hello", return "olleh".

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临时对象
class Solution {
public:
string reverseString(string s) {
int length=s.size();
string str_tmp(length,0);
int j=0;
for(int i=s.size()-1;i>=0;i--)
{
str_tmp[j++]=s[i];
}

return str_tmp;
}
};

原址交换

class Solution {
public:
string reverseString(string s) {
int j=s.size()-1;

for(int i=0;i<j;i++,j--)
{
swap(s[i],s[j]);
}

return s;
}
};
牛逼的C++

class Solution {
public:
string reverseString(string s) {
return string(s.rbegin(), s.rend());
}
};