GuessNumberHigherOrLower374.kt

package easy

import kotlin.random.Random

/**
 * We are playing the Guess Game. The game is as follows:

I pick a number from 1 to n. You have to guess which number I picked.

Every time you guess wrong, I will tell you whether the number I picked is higher or lower than your guess.

You call a pre-defined API int guess(int num), which returns three possible results:

-1: Your guess is higher than the number I picked (i.e. num > pick).
1: Your guess is lower than the number I picked (i.e. num < pick).
0: your guess is equal to the number I picked (i.e. num == pick).
Return the number that I picked.



Example 1:

Input: n = 10, pick = 6
Output: 6
Example 2:

Input: n = 1, pick = 1
Output: 1
Example 3:

Input: n = 2, pick = 1
Output: 1


Constraints:

1 <= n <= 231 - 1
1 <= pick <= n
 */
/**
 * The API guess is defined in the parent class.
 * @param  num   your guess
 * @return         -1 if num is lower than the guess number
 *			      1 if num is higher than the guess number
 *               otherwise return 0
 * fun guess(num:Int):Int {}
 */
class GuessNumber(n: Int) {
    val pick = Random.nextInt(1, n + 1)
    fun guess(num: Int): Int {
        return if (num > pick) -1
        else if (num < pick) 1
        else 0
    }

    fun guessNumber(n: Int): Int {
        var low = 1
        var high = n

        while (low <= high) {
            val mid = low + ((high - low) / 2)
            when {
                guess(mid) == -1 -> high = mid - 1
                guess(mid) == 1 -> low = mid + 1
                else -> return mid
            }
        }

        return -1
    }

}