Java Mergesortの文字列

Question

私はmergesortを使ってJavaのStringの配列を並べ替える方法を作ろうとしています。私はいくつかのコードサンプルを見て、独自のアルゴリズムを作ったが、うまくいかないようだし、問題を見つけるのが難しい。コードは次のようになります。

/* 
* Sorting methods, implemented using mergesort to sort the array of names 
* alphabetically 
*/ 
public String[] sort(String[] array) { 
    // check if the number of elements < 2 
    if (array.length > 1) { 

     // divide into two smaller arrays 
     // determine length of two smaller arrays 
     int arrLen1 = array.length; 
     int arrLen2 = array.length - arrLen1; 

     // populate smaller arrays with elements from initial array 
     String[] array1 = new String[arrLen1]; 
     String[] array2 = new String[arrLen2]; 

     for (int i = 0; i < arrLen1; i++) { 
      array[i] = array1[i]; 
     } 

     for (int i = arrLen1; i < array.length; i++) { 
      array[i] = array2[i]; 
     } 

     // now that we have the two halves, we can recursively call sort() on each to sort them 
     array1 = sort(array1); 
     array2 = sort(array2); 

     // three counters are needed to keep track of where we are in the arrays, one for pos in final array, and one for each of the two halves 
     // i => pos in main array 
     // j => pos in array1 
     // k => pos in array2 
     int i = 0, j = 0, k = 0; 

     while (array1.length != j && array2.length != k) { 
      if (array1[i].compareTo(array2[i]) < 0) { 
       // copy current element of array1 to final array as it preceeds array2's current element 
       array[i] = array1[j]; 

       // increment the final array so we dont overwrite the value we just inserted 
       i++; 
       // increment array1 which we took the element from so we dont compare it again 
       j++; 
      } 
      // If the element in array2 preceeds the element in array1 

      else { 
       // copy current element of array1 to final array as it preceeds array1's current element 
       array[i] = array2[j]; 
       // increment the final array so we dont overwrite the value we just inserted 
       i++; 
       // increment array2 which we took the element from so we dont compare it again 
       k++; 
      } 
     } 

     // at this point one of the sub arrays have been exhausted, and no more elements to compare 
     while (array1.length != j) { 
      array[i] = array1[j]; 
      i++; 
      j++; 
     } 

     while (array2.length != k) { 
      array[i] = array2[k]; 
      i++; 
      k++; 

     } 
    } 

    return array; 
} 

Answer 1

あなたが実際に比較する前に再帰的に並べ替えようとしているものではありますか。

あなたのコードが書かれているように、array1は常にarrayと等しく、array1に再びソートをします。