• 第一次写python


    这是一个在BJDP上学习Coding Kata的时候用到的一个练习,原来打算用Java写的,但是一想正好是学习的好机会。

    就用Python了。第一次,写的有些复杂。

    这个题目是关于购买图书的打折信息的。

    题目来源:

    http://codingdojo.org/cgi-bin/wiki.pl?KataPotter

      1 class Strategy:
      2     def __init__(self, items):
      3         self.items = items;
      4         self.rate = self.get_discount_rate();
      5    
      6     def get_discount_rate(self):
      7         if len(self.items) == 5:
      8             return 0.75;
      9         if len(self.items) == 4:
     10             return 0.8;
     11         if len(self.items) == 3:
     12             return 0.9;
     13         if len(self.items) == 2:
     14             return 0.95;
     15         return 1.0;
     16 
     17     def get_price(self):
     18         return self.total_price() * self.rate;
     19 
     20     def total_price(self):
     21         price = 0.0;
     22         for item in self.items:
     23             price += item.book.price;
     24         return price;
     25 
     26     def count(self):
     27         return len(self.items);
     28     
     29 
     30 class StrategyOptimizer:
     31     def optimize(self, strategies):
     32         found = False;
     33         while True:
     34             found = self.replace_53_with_44(strategies);
     35             if not found:
     36                 break;
     37         return strategies;
     38 
     39     def replace_53_with_44(self, strategies):
     40         strategyMap = {};
     41         strategyMap.clear();
     42         for i in range(0, len(strategies)):
     43             strategy = strategies[i];
     44             strategyMap[strategy.count()] = i;
     45 
     46         if (strategyMap != None and len(strategyMap) != 0):
     47             if (strategyMap.get(5, None) != None and strategyMap.get(3, None) != None):
     48                 self.move_book(strategies[strategyMap[5]], strategies[strategyMap[3]]);
     49                 return True;
     50         return False;
     51 
     52     def move_book(self, source, dest):
     53         item = self.findAnyDiff(source, dest);
     54         if item == None:
     55             return;
     56         source.items.remove(item);
     57         source.rate = source.get_discount_rate();
     58         dest.items.extend([item]);
     59         dest.rate = source.get_discount_rate();
     60         return;
     61     
     62     def findAnyDiff(self, source, dest):
     63         for item in source.items:
     64             if item not in dest.items:
     65                 return item;
     66         return None;
     67 
     68 class Book:
     69     def __init__(self, index, name, price):
     70         self.index = index;
     71         self.name = name
     72         self.price = price
     73 
     74 class Item:
     75     def __init__(self, book, count):
     76         self.book = book
     77         self.count = count
     78 
     79 class Cart:
     80     items = [];
     81     def add_item(self, item):
     82         self.items.append(item);
     83 
     84 def pick_most_books(cart):
     85     items = [];
     86     for i in range(0, len(cart.items)):
     87         item = cart.items[i];
     88         if item.count == 0:
     89             continue;
     90         items.append(Item(item.book, 1));
     91         cart.items[i].count -= 1;
     92     return items;
     93 
     94 def is_empty(cart):
     95     for item in cart.items:
     96         if item.count > 0:
     97             return False;
     98     return True;
     99 
    100 def count_price(strategies):
    101     price = 0;
    102     for s in strategies:
    103         price += s.get_price();
    104     return price;
    105 
    106 def find_best_solution(cart):
    107     strategies = [];
    108     price = 0.0;
    109     while not is_empty(cart):
    110         items = pick_most_books(cart);
    111         strategy = Strategy(items);
    112         strategies.append(strategy);
    113     return strategies;
    114 
    115 def count_best_price(cart):
    116     strategies = find_best_solution(cart);
    117     so = StrategyOptimizer();
    118     strategies = so.optimize(strategies)
    119     price = count_price(strategies);
    120     print(price);
    121 
    122 if __name__ == '__main__':
    123     item_1 = Item(Book("#1.", "Philosophy Stone", 8), 2);
    124     item_2 = Item(Book("#2.", "Secret Chamber", 8), 2);
    125     item_3 = Item(Book("#3.", "Prisoner of Azkaban", 8), 2);
    126     item_4 = Item(Book("#4.", "Goblet of Fire", 8), 1);
    127     item_5 = Item(Book("#5.", "The Order of Phoenix", 8), 1);
    128     
    129     cart = Cart();
    130     cart.add_item(item_1);
    131     cart.add_item(item_2);
    132     cart.add_item(item_3);
    133     cart.add_item(item_4);
    134     cart.add_item(item_5);
    135 
    136     count_best_price(cart);
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  • 原文地址:https://www.cnblogs.com/stephen-wang/p/3229953.html
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