## 1. Problem

374. Guess Number Higher or Lower

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

## 2. Solution

I solved this problem like this.

Using binary search logic, we can solve this problem so easily.

```
class Solution:
def guessNumber(self, n: int) -> int:
left, right = 1, n
while left <= right:
mid = (left + right) // 2
if guess(mid) == 0:
return mid
elif guess(mid) == -1:
right = mid - 1
else:
left = mid + 1
return -1
```