题目

方法一：连续双指针翻转

class Solution {
    public String reverseLeftWords(String s, int n) {
        StringBuffer sb = new StringBuffer(s);
        reverseWord(sb,0,n-1);
        reverseWord(sb,n,sb.length()-1);
        return sb.reverse().toString();
       
    }
    public void reverseWord(StringBuffer s , int start ,int end){
            while(start<end){
                char temp  = s.charAt(start);
                s.setCharAt(start,s.charAt(end));
                s.setCharAt(end,temp);
                start++;
                end  --;
            }
    }
            
}