java bucket sort
public static int[] bucketSort(int[] a) {
Queue<Integer>[] buckets = fillBuckets(a);
int[] sorted = readBuckets(buckets);
return sorted;
}
public static Queue<Integer>[] fillBuckets(int[] array) {
if(array.length == 0){
Queue<Integer>[] r = new Queue[0];
return r;
}
int vmin = array[0];
int vmax = array[0];
for(int i = 0; i < array.length; i++){
if(array[i] > vmax){
vmax = array[i];
}
if(array[i] < vmin){
vmin = array[i];
}
}
Queue<Integer>[] buckets = new Queue[vmax - vmin + 1];
for(int i = 0; i < buckets.length; i++){
buckets[i] = new LinkedList<Integer>();
}
for(int i = 0; i < array.length; i++){
buckets[array[i] - vmin].add(array[i]);
}
return buckets;
}
public static int[] readBuckets(Queue<Integer>[] buckets) {
if(buckets.length == 0){
int[] e = new int[0];
return e;
}
ArrayList<Integer> a = new ArrayList<Integer>();
for(int i = 0 ; i < buckets.length; i++){
while(buckets[i].peek() != null){
a.add(buckets[i].remove());
}
}
int[] result = new int[a.size()];
for(int i = 0; i < a.size(); i++){
result[i] = a.get(i);
}
return result;
}