Sahat Yalkabov - 2 months ago 12
Java Question

# Bidirectionnal Bubble Sort in Java?

I need to implement the bidirectional bubble sort in my code.

In other words

`in`
will go from left to right first carrying the largest value.

But when it reaches
`out`
, it should reverse and go from right to left carrying the smallest value.

I am advised to to implement another
`out`
index in addition the current one
.

This is what I have so far - just 2 loops. I am guessing I have to combine them somehow?

``````    public void bubbleSort() {
int out, in; // nElems in my case is 4, because I have 4 elements in my array

for(out=nElems-1; out>1; out--) // outer loop backward
for(in=out; in>1; in--) // inner loop backward
if(a[in] < a[in-1])
swap(in, in-1);

for(out=0; out<nElems; out++) // outer loop forward
for(in=0; in<out; in++) // inner loop forward
if(a[in] > a[in+1])
swap(in, in+1);
``````

``````    public void bidirectionalBubbleSort()
{
int left = 0, right = a.length-1;
while (left < right)
{
for (int pos = left; pos < right; pos++)
{
if (a[pos] > a[pos+1])
swap(pos, pos+1);
}
right--;

for (int pos = right; pos > left; pos--)
{
if (a[pos] < a[pos-1])
swap(pos, pos-1);
}
left++;
}
}
``````
Source (Stackoverflow)