374. Guess Number Higher or Lower (Leetcode || easy || Java)

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

SOLUTION:

/**
* 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);
*/

public class Solution extends GuessGame {
public int guessNumber(int n) {
int start = 1;//the range given to us is 1 to n
int end = n;

while(start <= end){//Applying binary search in the range
int mid = start + (end — start)/2;

int ans = guess(mid);//Calling the function as given in the question to check whether our mid is equal to or greater or smaller than the guess number

if(ans == 0){
return mid;
}
else if(ans == -1){
end = mid — 1;
}else{
start = mid + 1;
}
}
return -1;
}
}

Thank you for reading. If you have any queries, then please let me know in the comment section.