Health score of questions

The following parameters are used to calculate the health score of a question in the HackerEarth library:

• The number of times a question is used: This is calculated based on the number of tests in which a question is used.
• The number of times candidates attempted a question: This is calculated based on the number of times a problem is attempted by candidates.
• The number of users who solved a question: This is calculated based on the number of times a problem was solved fully or partially.
• Delta days: This is calculated based on the number of days that have passed since the problem was last used.
• Difficulty level: This is calculated based on the number of times a candidate solved/attempted a question.