Initial commit

Author: ju-c

LICENSE.txt

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+MIT License
+
+Copyright (c) 2021 Othneil Drew
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# Basic sorting algorithms using Python
+
+Basic sorting algorithms:
+
+- [Bubble Sort](sorting_algorithms/bubble_sort.py)
+- [Merge Sort](sorting_algorithms/merge_sort.py)
+- [Quicksort](sorting_algorithms/quicksort.py)
+
+## Resources
+
+**Big-O:**
+[Big-O Cheat Sheet: Array Sorting Algorithms](https://www.bigocheatsheet.com/#sorting)
+**Bubble Sort:**
+[Bubble Sort: An Archaeological Algorithmic Analysis ](https://users.cs.duke.edu/~ola/bubble/bubble.html)
+[Bubble Sort: Quick Tutorial and Implementation Guide](https://www.pythoncentral.io/bubble-sort-implementation-guide/)
+**Quicksort:**
+[Quicksort in python (from Ken's Blog)](http://www.99nth.com/~krm/blog/quicksort-python.html)
+[Quicksort in Python](https://stackabuse.com/quicksort-in-python/)
+**Merge Sort:**
+[Merge Sort: A Quick Tutorial and Implementation Guide](https://www.pythoncentral.io/merge-sort-implementation-guide/)
+
+## License
+
+Distributed under the MIT License. See `LICENSE.txt` for more information.
+
+## Contact
+
+Julien Cortesi - [@serializers](https://twitter.com/serializers) - [julienc.net](https://julienc.net) - julien.cortesi@potonmail.com

sorting_algorithms/bubble_sort.py

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+def bubble_sort(alist):
+
+    for i in range(len(alist)-1, 0, -1):
+        for j in range(i):
+            if alist[j] > alist[j+1]:
+                temp = alist[j]
+                alist[j] = alist[j+1]
+                alist[j+1] = temp
+
+    return alist
+
+
+list_to_sort = [147, -16, 18, 91, 44, 1, 8, 54, 31, 18]
+bubble_sort(list_to_sort)
+print(list_to_sort)

sorting_algorithms/merge_sort.py

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+def merge_sort(alist):
+    if len(alist) > 1:
+        left = alist[:len(alist) // 2]
+        right = alist[len(alist) // 2:]
+
+        merge_sort(left)
+        merge_sort(right)
+
+        i = 0
+        j = 0
+        k = 0
+
+        while i < len(left) and j < len(right):
+            if left[i] < right[j]:
+                alist[k] = left[i]
+                i += 1
+            else:
+                alist[k] = right[j]
+                j += 1
+            k += 1
+
+        while i < len(left):
+            alist[k] = left[i]
+            i += 1
+            k += 1
+
+        while j < len(right):
+            alist[k] = right[j]
+            j += 1
+            k += 1
+
+
+list_to_sort = [147, -16, 18, 91, 44, 1, 8, 54, 31, 18]
+merge_sort(list_to_sort)
+print(list_to_sort)

sorting_algorithms/quicksort.py

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+def quicksort(alist, lower, higher):
+    """
+    lo - index of the lower end in the range
+    hi - index of the higher end"""
+    if lower < higher:
+        p = partition(alist, lower, higher)
+        quicksort(alist, lower, p - 1)
+        quicksort(alist, p + 1, higher)
+
+
+def partition(alist, lower, higher):
+    """Partitions the list within the given range
+    alist - a list to partition
+    lower - index of the lower end in list to start partitioning from
+    higher - index of higher end in list to end the partitioning"""
+    pivot = alist[higher]
+    i = lower
+    j = lower
+
+    while j < higher:
+        if alist[j] <= pivot:
+            alist[i], alist[j] = alist[j], alist[i]
+            i += 1
+        j += 1
+
+    alist[i], alist[higher] = alist[higher], alist[i]
+
+    return i
+
+
+list_to_sort = [147, -16, 18, 91, 44, 1, 8, 54, 31, 18]
+last_index = len(list_to_sort) - 1
+quicksort(list_to_sort, 0, last_index)
+print(list_to_sort)