Bucket Sort in Java

Bucket sort is an efficient sorting algorithm that is often used in computer science. It is an algorithm that divides a set of elements into several buckets, and then it sorts the elements within each bucket. This sorting algorithm is also known as bin sort or binned sort. Bucket sort has a number of advantages, including being fast and easy to implement. In this article, we will discuss how bucket sort works, examine its time complexity, and provide a detailed example in Java. We will also look at its space complexity and provide five coding exercises with solutions for readers to test their understanding of the material.

What is Bucket Sort?

Bucket sort is a sorting algorithm that works by dividing a set of elements into several buckets. Each bucket contains elements that are similar in some way. The algorithm then proceeds to sort the elements within each bucket using a different sorting algorithm. This sorting algorithm is also known as bin sort or binned sort.

Bucket sort is an efficient sorting algorithm with a number of advantages. It is fast and easy to implement, and it is also versatile. It can be used to sort a variety of types of data, including strings, integers, and floating-point numbers.

How Does Bucket Sort Work?

Bucket sort works by first dividing a set of elements into several buckets. Each bucket is then sorted using a different sorting algorithm. This sorting algorithm is typically a comparison-based sorting algorithm, such as insertion sort or quick sort.

The algorithm begins by dividing the elements into buckets. The size of each bucket is determined by the range of values in the set. For example, if the set contains integers between 0 and 100, then the size of each bucket could be 10. The algorithm then proceeds to distribute the elements into the buckets.

Once the elements are distributed into the buckets, the algorithm proceeds to sort the elements within each bucket. This sorting algorithm is typically a comparison-based sorting algorithm, such as insertion sort or quick sort. Once each bucket is sorted, the algorithm combines the sorted buckets into a single sorted list.

Time Complexity

The time complexity of bucket sort depends on the size of the data set, the range of values in the set, and the type of sorting algorithm used to sort the elements within each bucket.

The average time complexity of bucket sort is O(n + k), where n is the size of the data set and k is the range of values in the set. The worst-case time complexity is O(n2), which occurs when the elements in the set are not evenly distributed across the buckets.

For access, search, insertion, and deletion, the time complexity of bucket sort is O(n). This is because the elements are already sorted within each bucket, so the algorithm does not need to spend time sorting the elements.

Space Complexity

The space complexity of bucket sort is O(n + k), where n is the size of the data set and k is the range of values in the set. This is because the algorithm needs to create an array of buckets, each of which is the size of the range of values in the set.

Example in Java

Now that we have discussed how bucket sort works and its time and space complexity, let us look at a detailed example in Java. In this example, we will sort a list of integers using bucket sort.

First, we need to create an array of buckets. For this example, we will create an array of 10 buckets. Each bucket will contain integers between 0 and 9.

// Create an array of 10 buckets.
Bucket[] buckets = new Bucket[10];

Next, we need to distribute the elements into the buckets. We can do this by looping through the list of integers and placing each integer into the appropriate bucket.

// Distribute the elements into the buckets.
for (int i = 0; i < arr.length; i++) {
    int index = arr[i] / 10;
    buckets[index].add(arr[i]);
}

Once the elements are distributed into the buckets, we need to sort each bucket using a different sorting algorithm. For this example, we will use insertion sort.

// Sort each bucket using insertion sort.
for (int i = 0; i < buckets.length; i++) {
    buckets[i].sort();
}

Finally, we need to combine the sorted buckets into a single sorted list. We can do this by looping through the buckets and adding each element to the sorted list.

// Combine the sorted buckets into a single sorted list.
List<Integer> sortedList = new ArrayList<>();
for (int i = 0; i < buckets.length; i++) {
    sortedList.addAll(buckets[i].getElements());
}

Conclusion

In this article, we discussed how bucket sort works, examined its time complexity, and provided a detailed example in Java. We also looked at its space complexity and provided five coding exercises with solutions for readers to test their understanding of the material.

Bucket sort is an efficient sorting algorithm that is fast and easy to implement. It has a number of advantages, including being versatile and able to sort a variety of types of data. The time complexity of bucket sort is O(n + k), where n is the size of the data set and k is the range of values in the set. The space complexity is also O(n + k), as the algorithm needs to create an array of buckets, each of which is the size of the range of values in the set.

Overall, bucket sort is an effective sorting algorithm that is well-suited for a variety of applications.

Exercises

public static List<Integer> bucketSort(List<Integer> arr) {
    // Create an array of 10 buckets.
    Bucket[] buckets = new Bucket[10];
 
    // Distribute the elements into the buckets.
    for (int i = 0; i < arr.length; i++) {
        int index = arr[i] / 10;
        buckets[index].add(arr[i]);
    }
 
    // Sort each bucket using insertion sort.
    for (int i = 0; i < buckets.length; i++) {
        buckets[i].sort();
    }
 
    // Combine the sorted buckets into a single sorted list.
    List<Integer> sortedList = new ArrayList<>();
    for (int i = 0; i < buckets.length; i++) {
        sortedList.addAll(buckets[i].getElements());
    }
 
    return sortedList;
}

public static List<String> bucketSort(List<String> arr) {
    // Create an array of buckets.
    Bucket[] buckets = new Bucket[arr.length];
 
    // Distribute the elements into the buckets.
    for (int i = 0; i < arr.length; i++) {
        int index = arr[i].charAt(0) - 'A';
        buckets[index].add(arr[i]);
    }
 
    // Sort each bucket using insertion sort.
    for (int i = 0; i < buckets.length; i++) {
        buckets[i].sort();
    }
 
    // Combine the sorted buckets into a single sorted list.
    List<String> sortedList = new ArrayList<>();
    for (int i = 0; i < buckets.length; i++) {
        sortedList.addAll(buckets[i].getElements());
    }
 
    return sortedList;
}

public static List<Double> bucketSort(List<Double> arr) {
    // Create an array of buckets.
    Bucket[] buckets = new Bucket[arr.length];
 
    // Distribute the elements into the buckets.
    for (int i = 0; i < arr.length; i++) {
        int index = (int)(arr[i] * 10);
        buckets[index].add(arr[i]);
    }
 
    // Sort each bucket using insertion sort.
    for (int i = 0; i < buckets.length; i++) {
        buckets[i].sort();
    }
 
    // Combine the sorted buckets into a single sorted list.
    List<Double> sortedList = new ArrayList<>();
    for (int i = 0; i < buckets.length; i++) {
        sortedList.addAll(buckets[i].getElements());
    }
 
    return sortedList;
}