I want to implement the Binary Quicksort algorithm from [Robert Sedgewick's book][1]. It looks like this:
public class quickb{
public static final int bitsword=32;
public static void quicksortB(int a[],int l,int r,int d){
int i=l;
int j=r;
if (r<=l || d>bitsword) return ;
while (j!=i)
{
while (digit(a[i],d)==0 && (i<j)) i++;
while (digit(a[j],d)==1 && (j>i)) j--;
int t=a[i];
a[i]=a[j];
a[j]=t;
}
if (digit(a[r],d)== 0) j--;
quicksortB(a,l,j-1,d+1);
quicksortB(a,j,r,d+1);
}
public static void main(String[]args){
int a[]=new int[]{4,7,3,9,8,2};
quicksortB(a,0,a.length-1,0);
for (int i=0;i<a.l开发者_开发技巧ength;i++){
System.out.println(a[i]);
}
}
public static int digit(int m,int d){
return (m>>d)&1;
}
}
i have changed it compiles but result is 4 8 9 3 7 2 maybe code is in correct in book can anybody help me to solve this problem?
With TJMonk15 correction (-- in the while).
I've tried to execute and that's what happens
The final array is 489372, with this "log":
Swapping (from left to right): 7 with 8
Swapping (from left to right): 3 with 3
Swapping (from left to right): 3 with 9
Swapping (from left to right): 3 with 3
Swapping (from left to right): 7 with 7
No swapping is correct according to me..
I don't understand why int j=r-1
and you use length-1
as r, then j is equal to length-2
at the beginning.
shouldn't
while (digit(a[j],d)==1 && (j>i)) j++;
be
while (digit(a[j],d)==1 && (j>i)) j--;
?
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