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.
考察Binary Search
1 /* The guess API is defined in the parent class GuessGame. 2 @param num, your guess 3 @return -1 if my number is lower, 1 if my number is higher, otherwise return 0 4 int guess(int num); */ 5 6 public class Solution extends GuessGame { 7 public int guessNumber(int n) { 8 int left = 1, right = n; 9 while (left + 1 < right) { 10 int mid = left + (right - left) / 2; 11 if (guess(mid) == 0) { 12 return mid; 13 } else if (guess(mid) == 1) { 14 left = mid; 15 } else { 16 right = mid; 17 } 18 } 19 if (guess(left) == 0) { 20 return left; 21 } else { 22 return right; 23 } 24 } 25 }
原文：http://www.cnblogs.com/FLAGyuri/p/5742929.html