add selection sort

dsa/chapter3/practice/selectionsort.py

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+def selectionsort(arr: list):
+    """
+    Let's implement selection sort! There are 4 easy steps to follow in order
+    to implement it.
+        1. Create a loop through iterate through the list.
+        2. Create an inner loop that iterates from the outer index + 1 to the
+           end of the list.
+        3. Compare the element at the outer index to the element at the inner
+           index.
+        4. If the element at the outer index is larger than at the inner index,
+           swap the 2 elements.
+    """
+
+    # Step 1, create an outer loop that iterates through the whole list. Let's
+    # name the outer index "i"
+
+    # Step 2, create an inner loop that iterates from i+1 to the end of the
+    # list, let's name inner index "j"
+
+    # Step 3, check if the element at index i is larger than the element at
+    # index j
+
+    # Step 4, swap the element at the outer index with the element at the
+    # inner index
+    pass
+
+
+if __name__ == "__main__":
+    lst = [-3, 5, -10, 18, 74, 22, 1, -40]
+    selectionsort(lst)
+    print(lst)

dsa/chapter3/solutions/selectionsort.py

@@ -0,0 +1,31 @@
+def selectionsort(arr: list):
+    """
+    Let's implement selection sort! There are 4 easy steps to follow in order
+    to implement it.
+        1. Create a loop through iterate through the list.
+        2. Create an inner loop that iterates from the outer index + 1 to the
+           end of the list.
+        3. Compare the element at the outer index to the element at the inner
+           index.
+        4. If the element at the outer index is larger than at the inner index,
+           swap the 2 elements.
+    """
+
+    # Step 1, create an outer loop that iterates through the whole list. Let's
+    # name the outer index "i"
+    for i in range(len(arr)):
+        # Step 2, create an inner loop that iterates from i+1 to the end of the
+        # list, let's name inner index "j"
+        for j in range(i+1, len(arr)):
+            # Step 3, check if the element at index i is larger than the
+            # element at index j
+            if arr[i] > arr[j]:
+                # Step 4, swap the element at the outer index with the element
+                # at the inner index
+                arr[i], arr[j] = arr[j], arr[i]
+
+
+if __name__ == "__main__":
+    lst = [-3, 5, -10, 18, 74, 22, 1, -40]
+    selectionsort(lst)
+    print(lst)