标签：
For this exercise you will be strengthening your page-fu mastery. You will complete the PaginationHelper class, which is a utility class helpful for querying paging information related to an array.
The class is designed to take in an array of values and an integer indicating how many items will be allowed per each page. The types of values contained within the collection/array are not relevant.
The following are some examples of how this class is used:
1 helper = PaginationHelper([‘a‘,‘b‘,‘c‘,‘d‘,‘e‘,‘f‘], 4) 2 helper.page_count # should == 2 3 helper.item_count # should == 6 4 helper.page_item_count(0) # should == 4 5 helper.page_item_count(1) # last page - should == 2 6 helper.page_item_count(2) # should == -1 since the page is invalid 7 8 # page_ndex takes an item index and returns the page that it belongs on 9 helper.page_index(5) # should == 1 (zero based index) 10 helper.page_index(2) # should == 0 11 helper.page_index(20) # should == -1 12 helper.page_index(-10) # should == -1 because negative indexes are invalid
进入6kyu 之后突然就吃力了些，感觉难起来的并不是编码，而是逻辑的完备性。
细心些，考虑各种非常规情况，超出处理阈值的情况，一定要——滴水不漏。
Python
1 # TODO: complete this class 2 3 class PaginationHelper: 4 5 # The constructor takes in an array of items and a integer indicating 6 # how many items fit within a single page 7 def __init__(self, collection, items_per_page): 8 self.collection = collection 9 self.items_per_page = items_per_page 10 11 12 # returns the number of items within the entire collection 13 def item_count(self): 14 return len(self.collection) 15 16 # returns the number of pages 17 def page_count(self): 18 if len(self.collection) % self.items_per_page == 0: 19 return len(self.collection) / self.items_per_page 20 else: 21 return len(self.collection) / self.items_per_page + 1 22 23 24 25 # returns the number of items on the current page. page_index is zero based 26 # this method should return -1 for page_index values that are out of range 27 def page_item_count(self,page_index): 28 if page_index >= self.page_count(): 29 return -1 30 elif page_index == self.page_count() - 1: 31 return len(self.collection) % self.items_per_page or self.items_per_page 32 else: 33 return self.items_per_page 34 35 36 37 # determines what page an item is on. Zero based indexes. 38 # this method should return -1 for item_index values that are out of range 39 def page_index(self,item_index): 40 if item_index >= len(self.collection) or item_index < 0: 41 return -1 42 else: 43 return item_index / self.items_per_page 44
【codewar-6kyu】PaginationHelper
标签：
原文地址：http://www.cnblogs.com/pudding-ai/p/5824222.html
