344. Reverse String

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

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

 

1.直接调用c++ STL 

reverse(s.begin(), s.end())

2.

class Solution {
public:
    string reverseString(string s) {
        int size = s.length();
        for(int i = 0, j = size - 1; i < j; i++, j--)
            swap(s[i], s[j]);
        return s;
    }
};

 

char* reverseString(char* s) {
    int i = 0, j = strlen(s) - 1, tmp;
    for(; i < j; i++, j--){
        tmp = s[i];
        s[i] = s[j];
        s[j] = tmp;
    }
    return s;
    
}