Codesignal Solution: nthPlace

Original Problem

My daughter was given the following task: given the first number x and the second number y, find the n^th number. The description was quite vague, but my daughter managed to do the task.

Can you?

Example

Turns out, for x = 7, y = 10 and n = 5,
the output should be
nthPlace(x, y, n) = 19.

Input/Output

• [time limit] 4000ms (js)

• [input] integer x

  The first number.

  Constraints:
  1 ≤ x ≤ y.

• [input] integer y

  The second number.

  Constraints:
  x ≤ y ≤ 100.

• [input] integer n

  The number to find.

  Constraints:
  3 ≤ n ≤ 50.

• [output] integer

  The n^th number.

Solution

The solution is simply \(n-1\) times the difference of the upper and lower bound plus the lower bound:

\[s = x + (y - x) \cdot (n - 1)\]

Or as a JavaScript solution:

nthPlace = (x, y, n) =>
   x + (y - x) * --n