1790.rotate-string-ii.cpp

//  Tag: String
//  Time: O(N)
//  Space: O(N)
//  Ref: -
//  Note: Simulation

//  Given a string（Given in the way of char array）, a right offset and a left offset, move the string cyclically according to the given offset and save it in a new result set for return.
//  （Left offest represents the offset of a string to the left,right offest represents the offset of a string to the right,the total offset is calculated from the left offset and the right offset, split two strings at the total offset and swap positions.）
//  
//  **Example 1:**
//  ```
//  Input：str ="abcdefg", left = 3, right = 1
//  Output："cdefgab"
//  Explanation：The left offset is 3, the right offset is 1, and the total offset is left 2. Therefore, the original string moves to the left and becomes "cdefg"+ "ab".
//  ```
//  
//  **Example 2:**
//  ```
//  Input：str="abcdefg", left = 0, right = 0
//  Output："abcdefg"
//  Explanation：The left offset is 0, the right offset is 0, and the total offset is 0. So the string remains unchanged.
//  ```
//  
//  
//  **Example 3:**
//  ```
//  Input：str = "abcdefg",left = 1, right = 2
//  Output："gabcdef"
//  Explanation：The left offset is 1, the right offset is 2, and the total offset is right 1. Therefore, the original string moves to the left and becomes "g" + "abcdef".
//  ```
//  
//  

class Solution {
public:
    /**
     * @param str: An array of char
     * @param left: a left offset
     * @param right: a right offset
     * @return: return a rotate string
     */
    string rotateString2(string &str, int left, int right) {
        // write your code here
        int length = str.size();
        int pos = (left - right) % length;
        pos = pos > 0 ? pos : length + pos;

        return str.substr(pos, length - pos) + str.substr(0, pos); // pos, length
    }
};