comefrom: <awangdev>493. Reverse Pairs_1.java
code: private int mergeSort(int[] nums, int start, int end) {
  
          if (start >= end) return 0;
          
          int mid = start + (end - start) / 2;
          int count = mergeSort(nums, start, mid) + mergeSort(nums, mid + 1, end);
          for (int i = start, j = mid + 1; i <= mid; i++) {
              while (j <= end && nums[i] / 2.0 > nums[j]) j++; 
              count += j - (mid + 1); 
          }
          
          Arrays.sort(nums, start, end + 1); 
          
          return count;
      }
masked: private int sample_funcname ( int [ ] nums , int start , int end ) {
    if ( start >= end ) return 0 ;
    int mid = start + ( end - start ) / 2 ;
    int count = mergeSort ( nums , start , mid ) + mergeSort ( nums , mid + 1 , end ) ;
    for ( int i = start , j = mid + 1 ;
    i <= mid ;
    i ++ ) {
      while ( j <= end && nums [ i ] / 2.0 > nums [ j ] ) j ++ ;
      count += j - ( mid + 1 ) ;
    }
    Arrays . sort ( nums , start , end + 1 ) ;
    return count ;
  }
  