字符串反转算法题

   今天聊一聊之前练过的算法题，有个学弟问我，我讲完了然后整理了整理，贴到博客园里：

    字符串反转  比如 “我爱你”，成了 “你爱我”

  哈哈哈，废话不多说，先哔哔下思路：

    I love you  应该这么玩儿 先把整个字符串 反转  uoy evol I  然后根据空格分出单词 单词再逐个 反转  you love I

秒懂了吧？

闲言碎语不要讲，上代码:

     

package TT;


public class Test1 {

    public static void rotateWord(char[] chas){
        
          if(chas.length ==0 || chas==null){
              return;
          }
          
       reverse(chas, 0, chas.length-1);
       
       int l =-1;
       int r = -1;
       for(int i =0; i<chas.length; i++){
           
           if(chas[i] !=' '){
               l = i ==0 ||chas[i-1]==' ' ? i : l;
               r = i ==chas.length-1 || chas[i+1] ==' ' ? i:r;
               
           }
           if(l!=-1 && r!=-1){
                reverse(chas,l,r);
                l = -1;
                r =-1;
           }
           
       }
        
    }
       
    public static void reverse(char[] chas, int start, int end){
         char tmp = 0;
         while(start <end){
             tmp = chas[start];
             chas[start]=chas[end];
             chas[end]=tmp;
             start++;
             end--;
             
         }
    }
    
    
    public static void main(String[] args){
        
        String a ="I love you";
        char[] b = a.toCharArray();
        System.out.println(a);
        rotateWord(b);
        String c = String.valueOf(b);
        System.out.println(c);
    }
    
    
    
      
      }
      

    
    

测试结果：

  

public class t1 {

    public static String revert(String string) {
        char[] chars = string.toCharArray();
        int left = 0;
        int right = chars.length - 1;
        while (left != right && left<=right && right>=0) {
            swap(left, right, chars);
            left++;
            right--;
        }
        String result = new String(chars);
        return result;
    }
  public static void swap(int x , int y , char[] chars){
      char temp = 'u0000';
      temp = chars[x];
      chars[x] = chars[y];
      chars[y] = temp;
  }

 public static void main(String[] args){
     String testStr = "123456789";
     String revertResult = revert(testStr);
     System.out.println(revertResult);

 }
}

这个解法主要在于while的控制， left<= right