Merge pull request #1 from donnemartin/master

update origin

README-zh-Hans.md

@@ -98,7 +98,7 @@
 
 > 各种系统设计主题的摘要，包括优点和缺点。**每一个主题都面临着取舍和权衡**。
 >
-> 每个章节都包含着更的资源的链接。
+> 每个章节都包含着更多的资源的链接。
 
 
 <p align="center">
@@ -108,7 +108,7 @@
 
 * [系统设计主题：从这里开始](#系统设计主题从这里开始)
     * [第一步：回顾可扩展性的视频讲座](#第一步回顾可扩展性scalability的视频讲座)
-    * [第二步： 回顾可扩展性的文章](#第二步回顾可扩展性文章)
+    * [第二步：回顾可扩展性的文章](#第二步回顾可扩展性文章)
     * [接下来的步骤](#接下来的步骤)
 * [性能与拓展性](#性能与可扩展性)
 * [延迟与吞吐量](#延迟与吞吐量)
@@ -207,7 +207,7 @@
 
 那些有经验的候选人通常会被期望了解更多的系统设计的知识。架构师或者团队负责人则会被期望了解更多除了个人贡献之外的知识。顶级的科技公司通常也会有一次或者更多的系统设计面试。
 
-面试会很宽泛的展开并在几个领域深入。这回帮助你了解一些关于系统设计的不同的主题。基于你的时间线，经验，面试的职位和面试的公司对下面的指导做出适当的调整。
+面试会很宽泛的展开并在几个领域深入。这会帮助你了解一些关于系统设计的不同的主题。基于你的时间线，经验，面试的职位和面试的公司对下面的指导做出适当的调整。
 
 * **短期** - 以系统设计主题的**广度**为目标。通过解决**一些**面试题来练习。
 * **中期** - 以系统设计主题的**广度**和**初级深度**为目标。通过解决**很多**面试题来练习。
@@ -242,9 +242,9 @@
 * 我们希望每秒钟处理多少请求？
 * 我们希望的读写比率？
 
-### 第二步：创造一个高级的设计
+### 第二步：创造一个高层级的设计
 
-使用所有重要的组件来描绘出一个高级的设计。
+使用所有重要的组件来描绘出一个高层级的设计。
 
 * 画出主要的组件和连接
 * 证明你的想法
@@ -273,11 +273,11 @@
 
 论述可能的解决办法和代价。每件事情需要取舍。可以使用[可拓展系统的设计原则](#系统设计主题的索引)来处理瓶颈。
 
-### 信封背面的计算
+### 预估计算量
 
 你或许会被要求通过手算进行一些估算。涉及到的[附录](#附录)涉及到的是下面的这些资源：
 
-* [使用信封的背面做计算](http://highscalability.com/blog/2011/1/26/google-pro-tip-use-back-of-the-envelope-calculations-to-choo.html)
+* [使用预估计算量](http://highscalability.com/blog/2011/1/26/google-pro-tip-use-back-of-the-envelope-calculations-to-choo.html)
 * [2 的次方表](#2-的次方表)
 * [每个程序员都应该知道的延迟数](#每个程序员都应该知道的延迟数)
 

README.md

@@ -1,4 +1,4 @@
-*[English](README.md) ∙ [日本語](README-ja.md) ∙ [简体中文](README-zh-Hans.md) ∙ [繁體中文](README-zh-TW.md) | [Brazilian Portuguese](https://github.com/donnemartin/system-design-primer/issues/40) ∙ [Italian](https://github.com/donnemartin/system-design-primer/issues/104) ∙ [Korean](https://github.com/donnemartin/system-design-primer/issues/102) ∙ [Persian](https://github.com/donnemartin/system-design-primer/issues/110) ∙ [Polish](https://github.com/donnemartin/system-design-primer/issues/68) ∙ [Russian](https://github.com/donnemartin/system-design-primer/issues/87) ∙ [Turkish](https://github.com/donnemartin/system-design-primer/issues/39) ∙ [Vietnamese](https://github.com/donnemartin/system-design-primer/issues/127) | [Add Translation](https://github.com/donnemartin/system-design-primer/issues/28)*
+*[English](README.md) ∙ [日本語](README-ja.md) ∙ [简体中文](README-zh-Hans.md) ∙ [繁體中文](README-zh-TW.md) | [Brazilian Portuguese](https://github.com/donnemartin/system-design-primer/issues/40) ∙ [Greek](https://github.com/donnemartin/system-design-primer/issues/130) ∙ [Italian](https://github.com/donnemartin/system-design-primer/issues/104) ∙ [Korean](https://github.com/donnemartin/system-design-primer/issues/102) ∙ [Persian](https://github.com/donnemartin/system-design-primer/issues/110) ∙ [Polish](https://github.com/donnemartin/system-design-primer/issues/68) ∙ [Russian](https://github.com/donnemartin/system-design-primer/issues/87) ∙ [Spanish](https://github.com/donnemartin/system-design-primer/issues/136) ∙ [Turkish](https://github.com/donnemartin/system-design-primer/issues/39) ∙ [Vietnamese](https://github.com/donnemartin/system-design-primer/issues/127) | [Add Translation](https://github.com/donnemartin/system-design-primer/issues/28)*
 
 # The System Design Primer
 

solutions/object_oriented_design/call_center/call_center.py

@@ -112,6 +112,11 @@ class CallCenter(object):
                 return employee
         return None
 
-    def notify_call_escalated(self, call):  # ...
+    def notify_call_escalated(self, call):
-    def notify_call_completed(self, call):  # ...
+        pass
-    def dispatch_queued_call_to_newly_freed_employee(self, call, employee):  # ...
+
+    def notify_call_completed(self, call):
+        pass
+
+    def dispatch_queued_call_to_newly_freed_employee(self, call, employee):
+        pass

solutions/object_oriented_design/deck_of_cards/deck_of_cards.py

@@ -68,7 +68,7 @@ class Hand(object):
 
     def score(self):
         total_value = 0
-        for card in card:
+        for card in self.cards:
             total_value += card.value
         return total_value
 
@@ -92,7 +92,7 @@ class BlackJackHand(Hand):
 
     def possible_scores(self):
         """Return a list of possible scores, taking Aces into account."""
-        # ...
+        pass
 
 
 class Deck(object):
@@ -102,9 +102,9 @@ class Deck(object):
         self.deal_index = 0
 
     def remaining_cards(self):
-        return len(self.cards) - deal_index
+        return len(self.cards) - self.deal_index
 
-    def deal_card():
+    def deal_card(self):
         try:
             card = self.cards[self.deal_index]
             card.is_available = False
@@ -113,4 +113,5 @@ class Deck(object):
             return None
         return card
 
-    def shuffle(self):  # ...
+    def shuffle(self):
+        pass

solutions/object_oriented_design/lru_cache/lru_cache.py

@@ -11,9 +11,14 @@ class LinkedList(object):
         self.head = None
         self.tail = None
 
-    def move_to_front(self, node):  # ...
+    def move_to_front(self, node):
-    def append_to_front(self, node):  # ...
+        pass
-    def remove_from_tail(self):  # ...
+
+    def append_to_front(self, node):
+        pass
+
+    def remove_from_tail(self):
+        pass
 
 
 class Cache(object):
@@ -24,9 +29,9 @@ class Cache(object):
         self.lookup = {}  # key: query, value: node
         self.linked_list = LinkedList()
 
-    def get(self, query)
+    def get(self, query):
         """Get the stored query result from the cache.
-        
+
         Accessing a node updates its position to the front of the LRU list.
         """
         node = self.lookup[query]
@@ -37,7 +42,7 @@ class Cache(object):
 
     def set(self, results, query):
         """Set the result for the given query key in the cache.
-        
+
         When updating an entry, updates its position to the front of the LRU list.
         If the entry is new and the cache is at capacity, removes the oldest entry
         before the new entry is added.
@@ -58,4 +63,4 @@ class Cache(object):
             # Add the new key and value
             new_node = Node(results)
             self.linked_list.append_to_front(new_node)
-            self.lookup[query] = new_node
+            self.lookup[query] = new_node

solutions/object_oriented_design/online_chat/online_chat.py

@@ -6,11 +6,20 @@ class UserService(object):
     def __init__(self):
         self.users_by_id = {}  # key: user id, value: User
 
-    def add_user(self, user_id, name, pass_hash):  # ...
+    def add_user(self, user_id, name, pass_hash):
-    def remove_user(self, user_id):  # ...
+        pass
-    def add_friend_request(self, from_user_id, to_user_id):  # ...
+
-    def approve_friend_request(self, from_user_id, to_user_id):  # ...
+    def remove_user(self, user_id):
-    def reject_friend_request(self, from_user_id, to_user_id):  # ...
+        pass
+
+    def add_friend_request(self, from_user_id, to_user_id):
+        pass
+
+    def approve_friend_request(self, from_user_id, to_user_id):
+        pass
+
+    def reject_friend_request(self, from_user_id, to_user_id):
+        pass
 
 
 class User(object):
@@ -25,12 +34,23 @@ class User(object):
         self.received_friend_requests_by_friend_id = {}  # key: friend id, value: AddRequest
         self.sent_friend_requests_by_friend_id = {}  # key: friend id, value: AddRequest
 
-    def message_user(self, friend_id, message):  # ...
+    def message_user(self, friend_id, message):
-    def message_group(self, group_id, message):  # ...
+        pass
-    def send_friend_request(self, friend_id):  # ...
+
-    def receive_friend_request(self, friend_id):  # ...
+    def message_group(self, group_id, message):
-    def approve_friend_request(self, friend_id):  # ...
+        pass
-    def reject_friend_request(self, friend_id):  # ...
+
+    def send_friend_request(self, friend_id):
+        pass
+
+    def receive_friend_request(self, friend_id):
+        pass
+
+    def approve_friend_request(self, friend_id):
+        pass
+
+    def reject_friend_request(self, friend_id):
+        pass
 
 
 class Chat(metaclass=ABCMeta):
@@ -51,8 +71,11 @@ class PrivateChat(Chat):
 
 class GroupChat(Chat):
 
-    def add_user(self, user):  # ...
+    def add_user(self, user):
-    def remove_user(self, user):  # ... 
+        pass
+
+    def remove_user(self, user):
+        pass
 
 
 class Message(object):
@@ -77,4 +100,4 @@ class RequestStatus(Enum):
     UNREAD = 0
     READ = 1
     ACCEPTED = 2
-    REJECTED = 3
+    REJECTED = 3

solutions/object_oriented_design/parking_lot/parking_lot.py

@@ -1,4 +1,5 @@
 from abc import ABCMeta, abstractmethod
+from enum import Enum
 
 
 class VehicleSize(Enum):
@@ -92,11 +93,11 @@ class Level(object):
 
     def _find_available_spot(self, vehicle):
         """Find an available spot where vehicle can fit, or return None"""
-        # ...
+        pass
 
     def _park_starting_at_spot(self, spot, vehicle):
         """Occupy starting at spot.spot_number to vehicle.spot_size."""
-        # ...
+        pass
 
 
 class ParkingSpot(object):
@@ -117,5 +118,8 @@ class ParkingSpot(object):
             return False
         return vehicle.can_fit_in_spot(self)
 
-    def park_vehicle(self, vehicle):  # ...
+    def park_vehicle(self, vehicle):
-    def remove_vehicle(self):  # ...
+        pass
+
+    def remove_vehicle(self):
+        pass

solutions/system_design/query_cache/query_cache_snippets.py

@@ -52,7 +52,7 @@ class Cache(object):
         self.lookup = {}
         self.linked_list = LinkedList()
 
-    def get(self, query)
+    def get(self, query):
         """Get the stored query result from the cache.
 
         Accessing a node updates its position to the front of the LRU list.

solutions/system_design/social_graph/social_graph_snippets.py

@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+from collections import deque
+
 
 class Graph(object):
 
@@ -61,3 +63,4 @@ class UserGraphService(object):
     def bfs(self, source, dest):
         # Use self.visited_ids to track visited nodes
         # Use self.lookup to translate a person_id to a Person
+        pass

solutions/system_design/web_crawler/web_crawler_snippets.py

@@ -2,33 +2,33 @@
 
 class PagesDataStore(object):
 
-    def __init__(self, db);
+    def __init__(self, db):
         self.db = db
-        ...
+        pass
 
     def add_link_to_crawl(self, url):
         """Add the given link to `links_to_crawl`."""
-        ...
+        pass
 
     def remove_link_to_crawl(self, url):
         """Remove the given link from `links_to_crawl`."""
-        ...
+        pass
 
-    def reduce_priority_link_to_crawl(self, url)
+    def reduce_priority_link_to_crawl(self, url):
         """Reduce the priority of a link in `links_to_crawl` to avoid cycles."""
-        ...
+        pass
 
     def extract_max_priority_page(self):
         """Return the highest priority link in `links_to_crawl`."""
-        ...
+        pass
 
     def insert_crawled_link(self, url, signature):
         """Add the given link to `crawled_links`."""
-        ...
+        pass
 
     def crawled_similar(self, signature):
         """Determine if we've already crawled a page matching the given signature"""
-        ...
+        pass
 
 
 class Page(object):
@@ -41,7 +41,7 @@ class Page(object):
 
     def create_signature(self):
         # Create signature based on url and contents
-        ...
+        pass
 
 
 class Crawler(object):