Features of best sorting algorithm

The ideal sorting algorithm would have the following properties:

• Stable: Equal keys aren't reordered.
• Operates in place, requiring O(1) extra space.
• Worst-case O(n·lg(n)) key comparisons.
• Worst-case O(n) swaps.
• Adaptive: Speeds up to O(n) when data is nearly sorted or when there are few unique keys.

Final: Question 1 , MongoDB

1. db.messages.find({"headers.From":"andrew.fastow@enron.com","headers.To":{$in:["jeff.skilling@enron.com"]}}).count()
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5. Question : 

1. Please download the Enron email dataset enron.zip, unzip it and then restore it using mongorestore. It should restore to a collection called "messages" in a database called "enron". Note that this is an abbreviated version of the full corpus. There should be 120,477 documents after restore.
   
   Inspect a few of the documents to get a basic understanding of the structure. Enron was an American corporation that engaged in a widespread accounting fraud and subsequently failed.
   
   In this dataset, each document is an email message. Like all Email messages, there is one sender but there can be multiple recipients.
   
   Construct a query to calculate the number of messages sent by Andrew Fastow, CFO, to Jeff Skilling, the president. Andrew Fastow's email addess was andrew.fastow@enron.com. Jeff Skilling's email was jeff.skilling@enron.com.
   
   For reference, the number of email messages from Andrew Fastow to John Lavorato (john.lavorato@enron.com) was 1.
   

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• db.messages.find({"headers.From":"andrew.fastow@enron.com","headers.To":{$in:["jeff.skilling@enron.com"]}}).count()Previous