Program to calculate Percentile of Students

Given an array containing marks of students, the task is to calculate the percentile of the students. The percentile is calculated according to the following rule: 
 

The percentile of a student is the % of the number of students having marks less than him/her.

Examples: 
 

Input: arr[] = { 12, 60, 80, 71, 30 }
Output: { 0, 50, 100, 75, 25 }
Explanation: 
Percentile of Student 1 = 0/4*100 = 0 (out of other 4 students no one has marks less than this student) 
Percentile of Student 2 = 2/4*100 = 50 (out of other 4 students, 2 have marks less than this student) 
Percentile of Student 3 = 4/4*100 = 100 (out of other 4 students, all 4 have marks less than this student) 
Percentile of Student 4 = 3/4*100 = 75 (out of other 4 students, 3 have marks less than this student) 
Percentile of Student 5 = 1/4*100 = 25 (out of other 4 students only 1 has marks less than this student) 
 

Approach: 
 

• So basically, the percentile is a number where a certain percentage of scores fall below that number. 
   
• For example: If in an examination a student's percentile is 75 then it means that the student has scored more than 75% of students who took the test. 
   
• Now, in order to calculate percentile we have the following formula:
  PERCENTILE = (NUMBER OF STUDENTS WHO SCORED BELOW OR EQUAL TO THE DESIRED STUDENT/ TOTAL NUMBER OF STUDENTS - 1) * 100 
   

Below is the implementation of the above approach:
 

Percentile of Student 1 = 0
Percentile of Student 2 = 50
Percentile of Student 3 = 100
Percentile of Student 4 = 75
Percentile of Student 5 = 25

Time Complexity: O(n²)

Auxiliary Space: O(1)