We are required to write a JavaScript function that takes in three numbers A, B and N, and finds the total number of N-digit numbers whose sum of digits at even positions and odd positions are divisible by A and B respectively.
Example
Let’s write the code for this function −
const indexSum = (num, sumOdd = 0, sumEven = 0, index = 0) => { if(num){ if(index % 2 === 0){ sumEven += num % 10; }else{ sumOdd += num % 10; }; return indexSum(Math.floor(num / 10), sumOdd, sumEven, ++index); }; return {sumOdd, sumEven}; }; const divides = (b, a) => a % b === 0; const countNum = (n, first, second) => { let start = Math.pow(10, (n-1)); const end = Math.pow(10, n)-1; const res = []; while(start <= end){ const { sumEven, sumOdd } = indexSum(start); const condition = divides(first, sumEven) && divides(second, sumOdd); if(condition){ res.push(start); }; start++; }; return res; }; console.log(countNum(2, 5, 3));
Output
Following is the output in the console −
[ 30, 35, 60, 65, 90, 95 ]