Python Puzzlers Series - Create Combination and Permutation Functions скачать в хорошем качестве

Python Puzzlers Series - Create Combination and Permutation Functions

Welcome back everybody. Today, our python puzzler challenge is to create functions that can answer the following two questions: 1. Jerry needs to choose 3 friends from a group of 9 friends to be on his bobsled team. How many ways can the selection be made? Hint: Order is not important. 2. Seven cars enter a race. How many possibilities are there for the first through third place finishers? Hint: Order is important. This puzzler is just to get the brain going and thinking about how to solve problems relating to combinations and permutations and the algorithms. There are probably more complicated but better ways to implement this in python. If you are not concerned about the algorithm - for large numbers/calculations - I would suggest using a package such as math, scipy, and/or gmpy2 for combinations and permutations and NOT using the python formula implementation. Examples: import itertools import math import gmpy2 from scipy.special import comb from scipy.special import perm print(len(list(itertools.combinations(range(1,10),3)))) print(math.comb(9,3)) print(comb(9,3, exact=True)) print(gmpy2.comb(9,3)) print(len(list(itertools.permutations(range(1,8),3)))) print(math.perm(7,3)) print(perm(7,3, exact=True)) itertools.permutations with big numbers might not run. Only the standard formulas are covered here. Does not include with replacement/with repetition, all possible, etc. Also, this function does not account for corner cases (error checking) like if you enter a larger choose number (r) than the total number (n), etc. math.comb and math.perm are new in version 3.8. Combinations are the number of different ways in which objects can be arranged without regard to order. Permutations are the number of different ways in which objects can be arranged in order. This puzzler level is easy. In this series we will include: data structures, algorithms, brain teasers, puzzles, and coding challenges. The purpose of these tutorials will be to: Help you improve your coding skills or knock off the rust. Help to improve your problem solving skills. Help you answer questions on sites like LeetCode, Codewars, HackerRank, etc. Help you prepare for interviews - if needed. And most importantly - have fun coding by solving brain teasers and puzzles.