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'll tell you whether the number is higher or lower.
You call a pre-defined API guess(int num) which returns 3 possible results (-1, 1, or 0):
-1 : My number is lower
1 : My number is higher
0 : Congrats! You got it!
Example:
n = 10, I pick 6.
Return 6.
Solutions:
/* The guess API is defined in the parent class GuessGame.
@param num, your guess
@return -1 if my number is lower, 1 if my number is higher, otherwise return 0
int guess(int num); */
public class Solution extends GuessGame {
public int guessNumber(int n) {
int left = 1, right = n;
while (left <= n) {
int mid = left + (right - left) / 2;
int g = guess(mid);
if (g == 0) {
return mid;
}
else if (g == 1) {
left = mid + 1;
}
else {
right = mid - 1;
}
}
return 0;
}
}