Problem74.js

// Problem 74
//
// This problem was asked by Apple.
//
// Suppose you have a multiplication table that is N by N. That is, a 2D array where the value at the i-th row and j-th column is (i + 1) * (j + 1) (if 0-indexed) or i * j (if 1-indexed).
//
// Given integers N and X, write a function that returns the number of times X appears as a value in an N by N multiplication table.
//
// For example, given N = 6 and X = 12, you should return 4, since the multiplication table looks like this:
//
// | 1 | 2 | 3 | 4 | 5 | 6 |
//
// | 2 | 4 | 6 | 8 | 10 | 12 |
//
// | 3 | 6 | 9 | 12 | 15 | 18 |
//
// | 4 | 8 | 12 | 16 | 20 | 24 |
//
// | 5 | 10 | 15 | 20 | 25 | 30 |
//
// | 6 | 12 | 18 | 24 | 30 | 36 |
//
// And there are 4 12's in the table.
//
// O(N) Time complexity
// O(1) Space complexity

/**
 * Returns the number of times x appears as a value in an N by N multipliation table
 * @param {number} n
 * @param {number} x
 * @return {number}
 */
function multiplicationTable(n, x) {
  let count = 0;
  for (let i = 1; i <= n; i++) {
    if (x % i === 0 && x / i <= n) {
      count++;
    }
  }
  return count;
}

export default multiplicationTable;