为什么我的字符数组的就地递归代码不适用于所有测试用例？ 我的代码有什么问题

Question

class Solution { 
    static int k=0; 
    static int l=0; 

    public void reverseString(char[] s) { 
        if(k==s.length||s==null){ 
            return; 
        }

        char c = s[k++]; 
        reverseString(s); 
        s[l++]=c; 
    } 
}

why my code of inplace recursion of character array is not working for all the test cases? is there any problem with my code

Answer 1

Instead of using a class that has to be instantiated to reverse the array, I would suggest the following:

class Solution {

   public static void reverseString(char[] str) {
      reverseStringImpl(str, 0);
   }

   private static void reverseStringImpl(char[] s, int k) {
      // details here
   }
}

I omitted the details (but the array and starting location are sufficient to accomplish this). This is still recursive but it hides the implementation and does not require any instance variables to maintain state . Nor does it require the user to pass the initial starting location of 0 to the method.