Finding the first n largest elements in an array

Question

I have got an array containing unique elements. I need to find out the first n largest elements in the array in the least complexity possible. The solution that I could thin

Answer 1

I don't believe on this but you could also create a heap out of it in O(n). And then just remove the root k number of times and heapify the heap for k largest numbers. In this way for each largest numbers it will cost you log(n).

public class HeapSort1{                                                          
    public static void main(String args[]){                                  
            int[] array={5,75,1,5,4,1,2,4,8,4,2,15,4,2,1,5,779,9,1};         
            int heapsize=array.length-1;                                     
            for(int i=heapsize/2;i>=0;i--){                                  
                    maxHeapify(array,i,heapsize);                            
            }                                                                
            for(int i=heapsize;i>0;i--){                                     
                    array[i]=array[0]+array[i];                              
                    array[0]=array[i]-array[0];                              
                    array[i]=array[i]-array[0];                              
                    maxHeapify(array,0,--heapsize);                          
            }                                                                
            printArray(array);                                               
    }                                                                        
    public static void maxHeapify(int[] array,int i,int heapsize){           
            int largest=i;                                                   
            int left=2*i+1;                                                  
            int right=2*i+2;                                                 
            if(left<=heapsize && array[left]>array[i]){                      
                    largest=left;                                            
            }                                                                
            if(right<=heapsize && array[right]>array[largest]){              
                    largest=right;                                           
            }                                                                
            if(largest!=i){                                                  
                    array[i]=array[largest]+array[i];                        
                    array[largest]=array[i]-array[largest];                  
                    array[i]=array[i]-array[largest];                        
                    maxHeapify(array,largest,heapsize);                      
            }                                                                
    }                                                                        
    public static void printArray(int[] array){                              
            System.out.print("\n [");                                        
            for(int i=0;i