Beautiful Days at the Movies

 

Solution in Javascript

const i = 20;
const j = 23;
const k = 6;

function beautifulDays(i, j, k) {

    let beautifulDay = 0;

    while(i<=j){ //'i' is starting day
            //num to String //string to array //reverse //array to string
        let a = i.toString().split('').reverse().join('');
        if((i-a) % k === 0){
            beautifulDay++;
        }
        i++;
    }
    console.log(beautifulDay);
}

beautifulDays(i,j,k); //2

 

 

Reference

www.hackerrank.com/challenges/beautiful-days-at-the-movies/problem