added selection sort algorithm (DhanushNehru#167)

Author: Tanishk04

Sorting/selectionsort.py

@@ -0,0 +1,30 @@
+"""
+Intuition is to pick smallest element every times loop proceeds
+"""
+
+def selectionSort(arr):
+    """
+    The selectionSort function implements the selection sort algorithm to sort an array in ascending
+    order.
+    
+    :param arr: The parameter `arr` is a list of elements that you want to sort using the selection sort
+    algorithm
+    
+    Time complexity: O(N^2), (where N = size of the array), for the best, worst, and average cases.
+    Space Complexity: O(1)
+    """
+    n = len(arr)
+    
+    for i in range(0,n-1):
+        min_idx = i
+        for j in range(i,n):
+            if arr[j] < arr[min_idx]:
+                min_idx = j
+        # at this point we have collected information which element is smallest (between i and n-1)and its index is stored in min_idx
+        arr[i], arr[min_idx] = arr[min_idx], arr[i]
+
+
+temp = input("Enter numbers separated by a comma:\n").strip()
+arr = [int(item) for item in temp.split(",")]
+selectionSort(arr)
+print(arr)