fix: fix bucket sort

Author: codejsha

java-algorithm/src/main/java/com/example/algorithm/sort/BucketSort.java

@@ -1,24 +1,39 @@
 package com.example.algorithm.sort;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.LinkedList;
 
 public class BucketSort {
     public static Double[] bucketSort(Double[] array) {
-        var size = array.length;
-        var bucket = new ArrayList<LinkedList<Double>>();
-        for (var i = 0; i < size; i++) {
-            bucket.add(new LinkedList<>());
+        int size = array.length;
+        double min = Arrays.stream(array).min(Double::compare).orElse(0.0);
+        double max = Arrays.stream(array).max(Double::compare).orElse(0.0);
+        double range = max - min;
+
+        // initialize buckets
+        ArrayList<LinkedList<Double>> buckets = new ArrayList<LinkedList<Double>>();
+        for (int i = 0; i < size; i++) {
+            buckets.add(new LinkedList<>());
         }
 
-        for (var k : array) {
-            var list = bucket.get((int) Math.floor(size * k));
-            list.add(k);
+        // distribute array elements into buckets
+        for (Double k : array) {
+            int index = (int) Math.floor(size * ((k - min) / range));
+            if (index == size) {
+                index--;
+            }
+            buckets.get(index).add(k);
         }
 
-        for (var i = 0; i < size; i++) {
-            InsertionSort.insertionSort(array);
+        // sort individual buckets using insertion sort
+        for (int i = 0; i < size; i++) {
+            Double[] bucketArray = buckets.get(i).toArray(new Double[0]);
+            InsertionSort.insertionSort(bucketArray);
+            buckets.set(i, new LinkedList<>(Arrays.asList(bucketArray)));
         }
-        return array;
+
+        // concatenate all buckets
+        return buckets.stream().flatMap(LinkedList::stream).toArray(Double[]::new);
     }
 }