Guess Number Higher or Lower
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# LeetCode #374: Guess Number Higher or Lower (C/C++).

easy

source: https://leetcode.com/problems/guess-number-higher-or-lower
C/C++ Solution to LeetCode problem 374. Guess Number Higher or Lower.

## Problem

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.

## Examples

### 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

## Solution

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 27 28 29 30 31 /** * Forward declaration of guess API. * @param num your guess * @return -1 if num is higher than the picked number * 1 if num is lower than the picked number * otherwise return 0 * int guess(int num); */ class Solution { public: int guessNumber(int n) { long long l = 0; long long h = n; int m, g; while (l <= h) { m = (int)((l + h) / 2); g = guess(m); if (g == 0) break; if (g == -1) h = m - 1; if (g == 1) l = m + 1; } return m; } };