旋转字符串

旋转字符串

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题目描述:
给定一个字符串str和一个偏移量,根据偏移量原地旋转字符串(从左向右旋转).

• char[] str = {'a','b','c'};
  tips:
• offset >= 0
• str的长度 >= 0
  原地旋转意味着需要在函数中更改字符串s.你不需要返回任何东西.

public class Solution {
    /**
     * @param str: An array of char
     * @param offset: An integer
     * @return: nothing
     */
    public void rotateString(char[] str, int offset) {
        // write your code here
        if(str == null || str.length == 0){
            return;
        }
        offset = offset % str.length;
        if(offset == 0){
            return;
        }
        int i = 0;
        char tmp;
        char nextTmp = str[0];
        int prevIndex = 0;

        for(int count = 0;count < str.length; count++){
            tmp = nextTmp;
            if(i < str.length - offset){
                i = i + offset;
            }else{
                i = i - str.length + offset;
            }
            if(i == prevIndex){
                str[i] = tmp;
                nextTmp = str[++i];
                prevIndex++;
            }else{
                nextTmp = str[i];
                str[i] = tmp;
            }
        }
    }
}

输入:
char[] str = {"abcdefg"}
offset = 3
输出:
"efgabcd"