Rotate string left

Title Description ： The left rotation of a string transfers several characters in front of the string to the end of the string . Please define a function to implement the left rotation operation of string . such as ： Input string “abcdefg” And number 2, This function will return the result of rotating two bits to the left "cdefgab"

Method 1 solution idea ： Since it's a string , We can use it string Member functions of type . Before the string n Insert characters at the end of the string , Then put the front of the front n Delete characters , That's all right. .

Code implementation ：

string reverseLeftWords(string s, int n) {
        for(int i=0;i<n;i++){
            s.push_back(s[i]);
        }
        s.erase(0,n);
        return s;

Insert and delete explanations ：

 

  Method 2: problem solving ideas ： The inversion interval is before n The string of ; The inversion interval is n Substring to the end ; Invert the entire string

Code implementation ：

string reveserLeftWords(string s,int n)
{
    revese(s.begin(),s.begin()+n);
    revese(s.begin()+n,s.end());
    revese(s.begin(),s,end());
    return s;
}