Help the bookseller !
Codewars Kata 16√
Description
Link: stock_list
A bookseller has lots of books classified in 26 categories labeled A, B, … Z. Each book has a code c of 3, 4, 5 or more capitals letters. The 1st letter of a code is the capital letter of the book category. In the bookseller’s stocklist each code c is followed by a space and by a positive integer n (int n >= 0) which indicates the quantity of books of this code in stock.
For example an extract of one of the stocklists could be: L = {“ABART 20”, “CDXEF 50”, “BKWRK 25”, “BTSQZ 89”, “DRTYM 60”}. or L = [“ABART 20”, “CDXEF 50”, “BKWRK 25”, “BTSQZ 89”, “DRTYM 60”] or …. You will be given a stocklist (e.g. : L) and a list of categories in capital letters e.g :
M = {“A”, “B”, “C”, “W”} or M = [“A”, “B”, “C”, “W”] or … and your task is to find all the books of L with codes belonging to each category of M and to sum their quantity according to each category.
For the lists L and M of example you have to return the string (in Haskell/Clojure a list of pairs):
(A : 20) - (B : 114) - (C : 50) - (W : 0) where A, B, C, W are the categories, 20 is the sum of the unique book of category A, 114 the sum corresponding to “BKWRK” and “BTSQZ”, 50 corresponding to “CDXEF” and 0 to category ‘W’ since there are no code beginning with W.
If L or M are empty return string is “” (Clojure should return an empty array instead).
Note: In the result codes and their values are in the same order as in M.
My solution
def stock_list(listOfArt, listOfCat):
if listOfArt == [] or listOfCat == []:
return ''
rst1 = []
for i in listOfCat:
cnt = 0
for j in listOfArt:
if i == j[0]:
j2 = j.split(' ')
cnt += int(j2[-1])
rst1.append('({} : {})'.format(i,cnt))
return ' - '.join(rst1[i] for i in range(len(rst1)))
b = ["ABAR 200", "CDXE 500", "BKWR 250", "BTSQ 890", "DRTY 600"]
c = ["A", "B"]
print(stock_list(b, c))
Given solutions
from collections import Counter
def stock_list(listOfArt, listOfCat):
if not listOfArt:
return ''
codePos = listOfArt[0].index(' ') + 1
cnt = Counter()
for s in listOfArt:
cnt[s[0]] += int(s[codePos:])
return ' - '.join('({} : {})'.format(cat, cnt[cat]) for cat in listOfCat)
def stock_list(stocklist, categories):
if not stocklist or not categories:
return ""
return " - ".join(
"({} : {})".format(
category,
sum(int(item.split()[1]) for item in stocklist if item[0] == category))
for category in categories)
Points
1 Counter类的目的是用来跟踪值出现的次数。
