Merge pull request #7 from udistructor/selection-sort-exercise

Selection sort exercise

Author: groverkds

Diff for: algorithms/7_SelectionSort/selection_sort_exercise.md

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+# Exercise: Selection Sort
+
+Implement a Multi-Level Sort of a given list of dictionaries based on a given sorting order. If user wants to sort dictionary based on First Key 'A', Then Key 'B', they shall pass list of keys in the order of  preference as a list ['A','B']. Your code should be able to sort list of dictionaries for any number of keys in sorting order list.
+
+Using this multi-level sort, you should be able to sort any list of dictionaries based on sorting order preference
+
+Example:
+A single dictionary entry contains two keys 'First Name' and 'Last Name'. the list should be sorted first based on 'First Name', then based on 'Last Name', w.r.t. common/same 'First Name' entries.
+
+for this, one shall past sorting order of preference list [ 'First Name' , 'Last Name' ]
+
+For this, Given the following sequence List:
+ 
+```
+[
+    {'First Name': 'Raj', 'Last Name': 'Nayyar'},
+    {'First Name': 'Suraj', 'Last Name': 'Sharma'},
+    {'First Name': 'Karan', 'Last Name': 'Kumar'},
+    {'First Name': 'Jade', 'Last Name': 'Canary'},
+    {'First Name': 'Raj', 'Last Name': 'Thakur'},
+    {'First Name': 'Raj', 'Last Name': 'Sharma'},
+    {'First Name': 'Kiran', 'Last Name': 'Kamla'},
+    {'First Name': 'Armaan', 'Last Name': 'Kumar'},
+    {'First Name': 'Jaya', 'Last Name': 'Sharma'},
+    {'First Name': 'Ingrid', 'Last Name': 'Galore'},
+    {'First Name': 'Jaya', 'Last Name': 'Seth'},
+    {'First Name': 'Armaan', 'Last Name': 'Dadra'},
+    {'First Name': 'Ingrid', 'Last Name': 'Maverick'},
+    {'First Name': 'Aahana', 'Last Name': 'Arora'}
+]
+```
+
+
+Your algorithm should generate sorted list:
+
+```
+[
+    {'First Name': 'Aahana', 'Last Name': 'Arora'}
+    {'First Name': 'Armaan', 'Last Name': 'Dadra'}
+    {'First Name': 'Armaan', 'Last Name': 'Kumar'}
+    {'First Name': 'Ingrid', 'Last Name': 'Galore'}
+    {'First Name': 'Ingrid', 'Last Name': 'Maverick'}
+    {'First Name': 'Jade', 'Last Name': 'Canary'}
+    {'First Name': 'Jaya', 'Last Name': 'Seth'}
+    {'First Name': 'Jaya', 'Last Name': 'Sharma'}
+    {'First Name': 'Karan', 'Last Name': 'Kumar'}
+    {'First Name': 'Kiran', 'Last Name': 'Kamla'}
+    {'First Name': 'Raj', 'Last Name': 'Nayyar'}
+    {'First Name': 'Raj', 'Last Name': 'Sharma'}
+    {'First Name': 'Raj', 'Last Name': 'Thakur'}
+    {'First Name': 'Suraj', 'Last Name': 'Sharma'}
+]
+```
+
+
+
+
+
+ [Solution](https://github.com/codebasics/data-structures-algorithms-python/blob/master/algorithms/7_SelectionSort/selection_sort_exercise_solution.py)

Diff for: algorithms/7_SelectionSort/selection_sort_exercise_solution.py

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+def multilevel_selection_sort(elements, sort_by_list):
+    for sort_by in sort_by_list[-1::-1]:
+        for x in range(len(elements)):
+            min_index = x
+            for y in range(x, len(elements)):
+                if elements[y][sort_by] < elements[min_index][sort_by]:
+                    min_index = y
+            if x != min_index:
+                elements[x], elements[min_index] = elements[min_index], elements[x]
+
+
+if __name__ == '__main__':
+    elements = [
+        {'First Name': 'Raj', 'Last Name': 'Nayyar'},
+        {'First Name': 'Suraj', 'Last Name': 'Sharma'},
+        {'First Name': 'Karan', 'Last Name': 'Kumar'},
+        {'First Name': 'Jade', 'Last Name': 'Canary'},
+        {'First Name': 'Raj', 'Last Name': 'Thakur'},
+        {'First Name': 'Raj', 'Last Name': 'Sharma'},
+        {'First Name': 'Kiran', 'Last Name': 'Kamla'},
+        {'First Name': 'Armaan', 'Last Name': 'Kumar'},
+        {'First Name': 'Jaya', 'Last Name': 'Sharma'},
+        {'First Name': 'Ingrid', 'Last Name': 'Galore'},
+        {'First Name': 'Jaya', 'Last Name': 'Seth'},
+        {'First Name': 'Armaan', 'Last Name': 'Dadra'},
+        {'First Name': 'Ingrid', 'Last Name': 'Maverick'},
+        {'First Name': 'Aahana', 'Last Name': 'Arora'}
+    ]
+
+    print(f'Given unsorted array:', *elements, sep='\n')
+    multilevel_selection_sort(
+        elements, ['First Name', 'Last Name'])
+    print(f'Array after Multi-Level Sorting:', *elements, sep='\n')