Merge pull request #207 from lck6055/Add-bucket-sort

Add Bucket Sort implementation in Python

Author: Pradeepsingh61

Python/algorithms/sorting/bucket_sort.py

@@ -0,0 +1,103 @@
+"""
+Algorithm: Bucket Sort
+Description: Sorts elements by distributing them into buckets, sorting each bucket, and then combining them
+Time Complexity: Worst - O(n^2)
+Space Complexity: O(n + k)
+Author: Kashyap
+Date: 2025-10-01
+"""
+
+def insertion_sort(bucket: list):
+    """
+    Sort a single bucket using Insertion Sort.
+    
+    We use Insertion Sort because buckets usually have few elements,
+    making it efficient for small arrays.
+    
+    Args:
+        bucket (list): List of numbers in a bucket
+    """
+    for current_index in range(1, len(bucket)):
+        current_value = bucket[current_index]
+        position = current_index - 1
+        
+        # Shift larger elements one position to the right
+        while position >= 0 and bucket[position] > current_value:
+            bucket[position + 1] = bucket[position]
+            position -= 1
+        bucket[position + 1] = current_value
+
+
+def bucket_sort(array: list):
+    """
+    Sort the input array using Bucket Sort.
+
+    Steps:
+    1. Create empty buckets. Each bucket will hold elements in a value range.
+    2. Distribute elements into buckets based on their value.
+    3. Sort each bucket individually.
+    4. Merge all sorted buckets back into the original array.
+    
+    Args:
+        array (list): List of numbers to be sorted
+
+    Example:
+        arr = [0.78, 0.17, 0.39, 0.26, 0.72]
+        bucket_sort(arr)
+        arr -> [0.17, 0.26, 0.39, 0.72, 0.78]
+    """
+    n = len(array)
+    if n == 0:
+        return 
+
+    buckets = [[] for _ in range(n)] # create the n empty lists
+
+    # Distribute elements into buckets
+    for value in array:
+        bucket_index = int(n * value)
+        if bucket_index == n:  # Edge case: value == 1
+            bucket_index = n - 1
+        buckets[bucket_index].append(value)
+
+    # Sort each bucket individually using insertion sort
+    for bucket in buckets:
+        insertion_sort(bucket)
+
+    # Merge all buckets into the original array
+    current_index = 0
+    for bucket in buckets:
+        for value in bucket:
+            array[current_index] = value
+            current_index += 1
+
+
+# -------------------------------
+# Main func and test cases
+# -------------------------------
+
+if __name__ == "__main__":
+    # Test case 1: 
+    test_array1 = [0.78, 0.17, 0.39, 0.26, 0.72, 0.94, 0.21, 0.12, 0.23, 0.68]
+    bucket_sort(test_array1)
+    print("Sorted array 1:", test_array1)  # [0.12, 0.17, 0.21, 0.23, 0.26, 0.39, 0.68, 0.72, 0.78, 0.94]
+
+    # Test case 2:
+    test_array2 = [0.1, 0.2, 0.3, 0.4, 0.5]
+    bucket_sort(test_array2)
+    print("Sorted array 2:", test_array2)  # [0.1, 0.2, 0.3, 0.4, 0.5]
+
+    # Test case 3:
+    test_array3 = [0.4, 0.2, 0.4, 0.1, 0.2]
+    bucket_sort(test_array3)
+    print("Sorted array 3:", test_array3)  # [0.1, 0.2, 0.2, 0.4, 0.4]
+
+    # Test case 4: 
+    test_array4 = []
+    bucket_sort(test_array4)
+    print("Sorted array 4:", test_array4)  # []
+
+    # Test case 5:
+    test_array5 = [0.5]
+    bucket_sort(test_array5)
+    print("Sorted array 5:", test_array5)  # [0.5]
+