/**
 * 
 * Ashish Patel
 * e: ashishsushilPatel@gmail.com
 * w: https://ashish.me
 *
 */

/* 
 * Given an array arr of integers, check if there exists two integers N and M
 * such that N is the double of M ( i.e. N = 2 * M).
 * 
 * More formally check if there exists two indices i and j such that :
 * 
 * i != j
 * 0 <= i, j < arr.length
 * arr[i] == 2 * arr[j]
 * 
 * Example 1:
 *
 * Input: arr = [10,2,5,3]
 * Output: true
 * Explanation: N = 10 is the double of M = 5,that is, 10 = 2 * 5.
*/

function checkIfNAndItsDoubleExist(nums) {
  let map = {}
  for (const num of nums) {
    if(map[num] > -Infinity) return true
    map[num*2] = num
    map[num/2] = num
  }
  return false
}

test('check If N And Its Double Exist', () => {
  expect(checkIfNAndItsDoubleExist([10,2,5,3])).toEqual(true)
});