Permutations using Python

Permutations

Did you know that the lock and key passwords work based on Permutations?

In lock patterns, order is what matters.

Combinations

In Combinations, order does not matter .

Permutations and Combinations in Python

Question:

Find the number of permutations and combinations that can be formed from the word HORSE taking two letters at a time.

Python Code

from itertools import combinations
from itertools import permutations 
import numpy as np
import math
arr=np.array(['H','O','R','S','E'])
print(len(list(combinations(arr, 2)) ))
print(len(list(permutations(arr,2) )))  

Result

10
20

Combinations with Factorial

Question:

In how many ways can 10 balls be picked, from 7 red out of 10, and 3 blue out of 8?

Python code

import math
red=math.factorial(10)/((math.factorial(7))*math.factorial(3))
blue=math.factorial(8)/((math.factorial(3))*math.factorial(5))
print(red*blue)

Result

6720