Merge pull request #339 from MrWeast/feature/radix-sort-python

Create radix_sort.py

Author: kelvins

README.md

@@ -3276,8 +3276,8 @@ In order to achieve greater coverage and encourage more people to contribute to
                 </a>
             </td>
             <td> <!-- Python -->
-                <a href="./CONTRIBUTING.md">
-                    <img align="center" height="25" src="./logos/github.svg" />
+                <a href="./src/python/radix_sort.py">
+                    <img align="center" height="25" src="./logos/python.svg" />
                 </a>
             </td>
             <td> <!-- Go -->

src/python/radix_sort.py

@@ -0,0 +1,55 @@
+import random
+
+
+def radix_sort(arr):
+    # Find the maximum number to know the number of digits
+    max_num = max(arr)
+
+    # Do counting sort for every digit, starting from the least significant digit
+    exp = 1
+    while max_num // exp > 0:
+        counting_sort(arr, exp)
+        exp *= 10
+
+
+def counting_sort(arr, exp):
+    n = len(arr)
+    output = [0] * n
+    count = [0] * 10
+
+    for i in range(n):
+        index = arr[i] // exp
+        count[index % 10] += 1
+
+    for i in range(1, 10):
+        count[i] += count[i - 1]
+
+    i = n - 1
+    while i >= 0:
+        index = arr[i] // exp
+        output[count[index % 10] - 1] = arr[i]
+        count[index % 10] -= 1
+        i -= 1
+
+    for i in range(n):
+        arr[i] = output[i]
+
+
+def main():
+    print("Fixed Testing Array")
+    arr = [170, 2, 45, 75, 75, 90, 802, 24, 2, 66]
+    print("Unsorted array:", arr)
+    radix_sort(arr)
+    print("Sorted array:", arr)
+
+    print("Random Testing Array")
+    arr = []
+    for i in range(0, 10):
+        arr.append(random.randint(0, 20))
+    print("Unsorted array:", arr)
+    radix_sort(arr)
+    print("Sorted array:", arr)
+
+
+if __name__ == "__main__":
+    main()