leetCode165|左旋转字符串

示例 1：

输入: s = "abcdefg", k = 2
输出: "cdefgab"
示例 2：

输入: s = "lrloseumgh", k = 6
输出: "umghlrlose"
 

限制：

1 <= k < s.length <= 10000

 

import java.util.LinkedList;
import java.util.List;

public  class ReverseLeftWordsTest {
    public static void main(String[] args) {
        String str = "abcdefg";
        int k = 2;
        String reverseLeftWords = reverseLeftWords(str, k);
        System.out.println("reverseLeftWords = " + reverseLeftWords);
    }

    public static String reverseLeftWords(String s, int n) {
        if (s == null || s.length() == 0 || "".equals(s) || s.length() < n) {
            return s;
        }
        List<Character> list = new LinkedList<>();
        for (int i = 0; i < n; i++) {
            char c = s.charAt(i);
            list.add(c);
        }
        String substring = s.substring(n);
        StringBuilder stringBuilder = new StringBuilder();
        for (Character c : list) {
            stringBuilder.append(c);
        }
        return substring + stringBuilder.toString();
    }
}