Find top N elements in an Array

Question

What would be the best solution to find top N (say 10) elements in an unordered list (of say 100).

The solution which came in my head was to 1. sort it using quick s

Answer 1

Written below both selection sort and insertion sort implementations. For larger data set I suggest insetion sort better than selection sort

public interface FindTopValues
{
  int[] findTopNValues(int[] data, int n);
}

Insertion Sort Implementation:

public class FindTopValuesInsertionSortImpl implements FindTopValues {  

/**
 * Finds list of the highest 'n' values in the source list, ordered naturally, 
 * with the highest value at the start of the array and returns it 
 */
@Override
public int[] findTopNValues(int[] values, int n) {

    int length = values.length;
    for (int i=1; i 0) && (values[i] > values[curPos-1])) {
            curPos--;
        }

        if (curPos != i) {
            int element = values[i];
            System.arraycopy(values, curPos, values, curPos+1, (i-curPos));
            values[curPos] = element;
        }
    }       

    return Arrays.copyOf(values, n);        
}   

}

Selection Sort Implementation:

public class FindTopValuesSelectionSortImpl implements FindTopValues {

/**
 * Finds list of the highest 'n' values in the source list, ordered naturally, 
 * with the highest value at the start of the array and returns it 
 */
@Override
public int[] findTopNValues(int[] values, int n) {
    int length = values.length;

    for (int i=0; i<=n; i++) {
        int maxPos = i;
        for (int j=i+1; j values[maxPos]) {
                maxPos = j;
            }
        }

        if (maxPos != i) {
            int maxValue = values[maxPos];
            values[maxPos] = values[i];
            values[i] = maxValue;
        }           
    }
    return Arrays.copyOf(values, n);        
}
}