374.Guess Number Higher or Lower

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Solution 1: accepted 1ms

The most standard binary search. 

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public class Solution extends GuessGame {
    public int guessNumber(int n) {
        int lo = 1;
        int hi = n;
        while (lo + 1 < hi) {
            int mid = lo + (hi - lo) / 2;
            System.out.println(mid);
            if (guess(mid) > 0) {
                lo = mid;
            } else if (guess(mid) < 0) {
                hi = mid;
            } else {
                return mid;
            }
        }
        
        if (guess(lo) == 0) {
            return lo;
        } else if (guess(hi) == 0) {
            return hi;
        } else {
            return 0;
        }
    }
}