[Jianzhi offer] 58 - ii Rotate string left

The finger of the sword Offer 58 - II. Left rotation string

subject

  The left rotation operation of string is to transfer several characters in front of string to the end of 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".

Ideas

• Before reversal N character string
• reverse n String after
• Invert the entire string

Code

class Solution {
    
public:
    string reverseLeftWords(string s, int n) {
    
        //  Before reversal N character string 
        reverse(s.begin(),s.begin() + n);

        //  reverse n String after 
        reverse(s.begin() + n,s.end());

        //  Invert the entire string 
        reverse(s.begin(),s.end());

        return s;
    }
};