1.O(nlogk)海量数据

 1 import java.util.TreeSet;

 2

 3 public class T030 {

 4     public static void main(String[] args){

 5         int[] data = {4,5,1,6,2,7,3,8};

 6         TreeSet<Integer> leastNumbers = new TreeSet<Integer>();

 7         getLeastNumbers(data,leastNumbers,4);

 8

 9     }

10     public static void getLeastNumbers(int[] data,TreeSet<Integer> leastNumbers,int k){

11         leastNumbers.clear();

12         if(k<1||data.length<k)

13             return;

14

15         for(int i=0;i<data.length;i++){

16             if(leastNumbers.size()<k)

17                 leastNumbers.add(data[i]);

18             else{

19                 System.out.println(leastNumbers.last().hashCode());

20                 if(data[i]<leastNumbers.last().hashCode()){

21                     leastNumbers.remove(leastNumbers.last());

22                     leastNumbers.add(data[i]);

23                 }

24

25             }

26         }

27         System.out.println(leastNumbers.toString());

28     }

29 }

java实现——030最小的k个数