Improve code on f-strings and brevity (#6126)

* Update strassen_matrix_multiplication.py

* Update matrix_operation.py

* Update enigma_machine2.py

* Update enigma_machine.py

* Update enigma_machine2.py

* Update rod_cutting.py

* Update external_sort.py

* Update sol1.py

* Update hill_cipher.py

* Update prime_numbers.py

* Update integration_by_simpson_approx.py