# Guess Number Higher Or Lower Problem

## Description

LeetCode Problem 374.

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 3 possible results:

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

Return the number that I picked.

Example 1:

1
2

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

Example 2:

1
2

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

Example 3:

1
2

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

Example 4:

1
2

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

Constraints:

- 1 <= n <= 2^31 - 1
- 1 <= pick <= n

## Sample C++ Code

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26

/**
* Forward declaration of guess API.
* @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
* int guess(int num);
*/
class Solution {
public:
int guessNumber(int n) {
int maxNumber = n, minNumber = 1;
while (true) {
int meanNumber = (maxNumber - minNumber) / 2 + minNumber;
int res = guess(meanNumber);
if (res == 0) {
return meanNumber;
} else if (res == 1) {
minNumber = meanNumber + 1;
} else {
maxNumber = meanNumber - 1;
}
}
}
};