[The Daily Byte][Student Averages]

gistfile1.txt

Question from: https://thedailybyte.dev/

// You are given a two-dimensional matrix that represents the grades of a class of students. Each grade is represented as an array where the first index is the student’s ID and the second student is a grade (0 - 100) that the student has received. Given these grades, calculate the average of each student’s top five scores and return the result.
// Note: Each student is guaranteed to have at least 5 scores. Student IDs start from zero and increase by one. Your return variable should be sorted according to student ID.

My solution:

const grades = [[1, 100], [1, 50], [2, 100], [2, 93], [1, 39], [2, 87], [1, 89], [1, 87], [1, 90], [2, 100], [2, 76]]

const averageGrade = (grades) => {
    let studentGrades = {}
    let result = []
    for (let i = 0; i < grades.length; i++) {
        const [studentId, grade] = grades[i]
        if (studentGrades[studentId]) {
            studentGrades[studentId].push(grade)
        } else {
            studentGrades[studentId] = [grade]
        }
    }
    for (let key in studentGrades) {
        studentGrades[key].sort((a, b) => b - a)
        let sum = 0
        for (let i = 0; i < 5; i++) {
            sum += studentGrades[key][i]
        }
        result.push([parseInt(key), Math.floor(sum / 5)])
    }
    return result
}

console.log(averageGrade(grades)) // [[1, 83], [2, 91]]