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Copy pathsolution40_2.java
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63 lines (57 loc) · 1.43 KB
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package nowcoder;
import java.util.ArrayList;
public class solution40_2 {
public ArrayList<Integer> GetLeastNumbers_Solution(int [] input, int k) {
ArrayList<Integer> ret = new ArrayList<>();
if(k>input.length||k<=0)
{
return ret;
}
findKthSmallth(input,k-1);
for(int i = 0;i<k;i++)
{
ret.add(input[i]);
}
return ret;
}
private void findKthSmallth(int[] input, int k) {
int l = 0;
int h = input.length -1;
while(l<h)
{
int j = partition(input,l,h);
if(j==k)
{
break;
}
if(j>k)//j的左边的数都比j小 j右边的数都比j大
{
h = j-1;
}else{
l = j+1;
}
}
}
private int partition(int[] input, int l, int h) {
int p = input[l];
int i = l,j = h+1;
while(true)
{
while(i!=h&&input[++i]<p);//从左往右依次找到比p大的数
while(j!=l&&input[--j]>p);//从右往左依次找到比p小的数
if(i>=j)//交叉点
{
break;
}
swap(input,i,j);
}
swap(input,l,j);
return j;
}
private void swap(int[] nums,int i,int j )
{
int t = nums[i];
nums[i] = nums[j];
nums[j] = t;
}
}