Please dont let the length of this post scare you! Okay so here is the prompt I am currently working on:
"Write a class named BucketSort containing a method called sort that:
a) Place each value of the one-dimensional array into a row of the bucket array, based on the value’s “ones” (rightmost) digit. For example, 97 is placed in row 7, 3 is placed in row 3 an 100 is placed in row 0. This procedure is called a distribution pass.
b) Loop through the bucket array row by row, and copy the values back to the original array. This procedure is called a gathering pass. The new order of the preceding values in the one-dimensional array is 100, 3 and 97.
c) Repeat this process for each subsequent digit position (tens, hundreds, thousands, etc.) On the second (tens digit) pass, 100 is placed in row 0, 3 is placed in row 0 (because 3 has no tens digit) and 97 is placed in row 9. After the gathering pass, the order of the values in the one-dimensional array is 100, 3 and 97. On the third (hundreds digit) pass, 100 is placed in row 1, 3 is placed in row 0 and 97 is placed in row 0 (after the 3) After this last gathering pass, the original array is in sorted order. being sorted.
This sorting technique provides better performance than a bubble sort,but requires much more memory—the bubble sort requires space for only one additional element of data. This comparison is an example of the space/time trade-off: The bucket sort uses more memory than the bubble sort, but performs better. This version of the bucket sort requires copying all the data back to the original array on each pass. Another possibility is to create a second two-dimensional bucket array and repeatedly swap the data between the two bucket arrays. The two-dimensional array of buckets is 10 times the length of the integer array"
A bit of a mouth full I know. Below is my code thus far, but I can't figure out why it will not print in the correct order and I think it is time for fresh eyes. Any ideas are appreciated, thanks!
import java.util.Arrays;
public class BucketSort_main {
public static void main(String[] args)
{
int[] numbers = new int [5];
int[] tnumbers = new int [500];
int [][] bucket = new int [10][numbers.length];
int [] a = new int [10];
int count = 0;
int divisor = 1;
int cnt = 1;
boolean moreDigits = true;
for (int s = 0; s < 10; s++)
{
a[s] = 0;
}
for (int b = 0; b < numbers.length; b++)
{
numbers [b] = (int)(Math.random()*2000);
tnumbers [b] = numbers [b];
}
int[] tmpSort = new int[10];
while (moreDigits)
{
moreDigits = false;
for (int i = 0; i < tmpSort.length; i++)
{
tmpSort[i]= -1; // hint hint
}
for (int i = 0; i < numbers.length; i++)
{
int tmp = tnumbers[i] / divisor;
if (tmp/10 != 0)
{
moreDigits = true;
}
int digit = tmp % 10;
tmpSort[digit] = tnumbers[i]; // hint hint
System.out.println("Number["+i+"], Digit "+cnt+" is "+digit + ". Full number = " + tnumbers[i]);
bucket [digit][a[digit]] = tnumbers[i];
System.out.println ("Digit " + digit + " going to slot " + a[digit] + ". " + bucket[digit][a[digit]]);
System.out.println (" ");
a[digit]++;
}
cnt++;
divisor *= 10;
for (int x = 0; x < 10; x++)
{
a [x] = 0;
for (int y = 0; y < numbers.length; y++)
{
if (bucket[x][y] != 0)
{
tnumbers [y] = 0;
tnumbers [y] = bucket[x][y];
bucket[x][y] = 0;
}
}
}
}
for (int o = 0; o < numbers.length; o++)
{
System.out.println (tnumbers[o]);
}
}
}
The Problem is here:
for (int x = 0; x < 10; x++)
{
a [x] = 0;
for (int y = 0; y < numbers.length; y++)
{
if (bucket[x][y] != 0)
{
tnumbers [y] = 0;
tnumbers [y] = bucket[x][y];
bucket[x][y] = 0;
}
}
}
You are using the same y to get values from the bucket and assign values to tnumbers. So, when you loop through y the second time you are starting over again at tnumbers[0], tnumbers[1], etc...
Fix this issue and your code works fine.