Ruby solution for Bakery coding challenge.
Install Ruby and clone the repo.
Ensure command
ruby --versionhas output like
ruby 2.2.3p173Script main.rb inputs data from STDIN and outputs to STDOUT. You can use
sample data or create own.
Run script:
cd bakery
ruby main.rb < test.sampleEnsure you got something like
10 VS5 $17.98
2 x 5 $8.99
14 MB11 $54.8
1 x 8 $24.95
3 x 2 $9.95
13 CF $25.85
2 x 5 $9.95
1 x 3 $5.95
...Bakery problem is a kind of
Change making problem
which is Knapsack type problem.
In terms of the problem, order amount is amount and pack sizes is
coin denominations which quantity is N.
There are two most common ways to solve the problem - Dynamic programming and Backtracking.
Dynamic programming solution calculates each amount last pack as min(packs)
of previously calculated amounts: amount - pack1..amount - packN.
Iterative solution should calculate all mins from 1 to amount so it requires:
O( amount * N )timeO( amount + N )memory
Backtracking solution uses idea of greedy full search and usually much slower
than Dynamic programming solution for big N because it is
NP-hard.
But Bakery problem has very small N (2..3) and "unlimited" amount. Thus
Backtracking solution requires:
O( amount / pack1 )worst time for 2 pack productsO( ( amount / pack1 ) * ( amount / pack2 ) )worst time for 3 pack productsO( N )memory
So Backtracking was choosen for the Bakery as most time and memory effective solution.