SelectionSort.py

Author: hashfx

DSA-Python/Algorithms/SelectionSort.py

@@ -0,0 +1,45 @@
+"""
+Selection Sort
+
+Time Complexity: O(n^2)
+"""
+
+def FindMin(arr):
+    """finds minimum element from the list"""
+    min = 100000  # let list contain +ve numbers only: so minimum number is -1
+    for i in range(len(arr)):
+        if arr[i] < min:
+            min = arr[i]
+    return min
+
+
+def SelectionSort(arr):
+    size = len(arr)
+    for i in range(size-1):  # decreased 1 iteration: no need to iterate to the last element
+        minIndex = i  # pointer initialised to ith index for selection sort
+        for j in range(minIndex+1, size):
+            if arr[j] < arr[minIndex]:  # if current index < minimum index of the array
+                minIndex = j  # minimum index updated
+        # swapping element
+        if i != minIndex:
+            arr[i], arr[minIndex] = arr[minIndex], arr[i]
+
+if __name__ == '__main__':
+    elements = [100, 19, 28, 14, 6, 1, 99]
+    print(FindMin(elements))  # prints minimum element from the list
+    SelectionSort(elements)
+    print(elements)
+
+    # running test cases
+
+    tests = [
+        [89, 78, 61, 23, 21, 53, 12, 1, 2, 6, 3, 17, 9],
+        [],
+        [1, 2, 3, 4, 5],
+        [350, 3, 1, 99, 12, 78, 12, 1200],
+        [9]
+    ]
+    # print("Tests case testing...")
+    for elements in tests:
+        SelectionSort(elements)
+        print(elements)