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  1. // Merge sort in Java
  2.  
  3. class MergeSort {
  4.   void merge(int arr[], int p, int q, int r) {
  5.  
  6.     int n1 = q - p + 1;
  7.     int n2 = r - q;
  8.  
  9.     int L[] = new int[n1];
  10.     int M[] = new int[n2];
  11.  
  12.     for (int i = 0; i < n1; i++)
  13.       L[i] = arr[p + i];
  14.     for (int j = 0; j < n2; j++)
  15.       M[j] = arr[q + 1 + j];
  16.  
  17.     int i, j, k;
  18.     i = 0;
  19.     j = 0;
  20.     k = p;
  21.     while (i < n1 && j < n2) {
  22.       if (L[i] <= M[j]) {
  23.         arr[k] = L[i];
  24.         i++;
  25.       } else {
  26.         arr[k] = M[j];
  27.         j++;
  28.       }
  29.       k++;
  30.     }
  31.     while (i < n1) {
  32.       arr[k] = L[i];
  33.       i++;
  34.       k++;
  35.     }
  36.  
  37.     while (j < n2) {
  38.       arr[k] = M[j];
  39.       j++;
  40.       k++;
  41.     }
  42.   }
  43.   void mergeSort(int arr[], int l, int r) {
  44.     if (l < r) {
  45.       int m = (l + r) / 2;
  46.  
  47.       mergeSort(arr, l, m);
  48.       mergeSort(arr, m + 1, r);
  49.       merge(arr, l, m, r);
  50.     }
  51.   }
  52.  
  53.   static void printArray(int arr[]) {
  54.     int n = arr.length;
  55.     for (int i = 0; i < n; ++i)
  56.       System.out.print(arr[i] + " ");
  57.     System.out.println();
  58.   }
  59.   public static void main(String args[]) {
  60.     int arr[] = { 6, 5, 12, 10, 9, 1 };
  61.  
  62.     MergeSort ob = new MergeSort();
  63.     ob.mergeSort(arr, 0, arr.length - 1);
  64.  
  65.     System.out.println("Sorted array:");
  66.     printArray(arr);
  67.   }
  68. }
Success #stdin #stdout 0.08s 34000KB
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Standard input is empty
stdout
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Sorted array:
1 5 6 9 10 12
https://ideone.com/razRE5
language:
Java (HotSpot 12)
created:
3 years ago
visibility:
public

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