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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.
思路：
二分查找即可，注意中间数值不能溢出，因此(high + low) / 2写成low + (high - low) / 2。
解法：
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 7 public class Solution extends GuessGame 8 { 9 public int guessNumber(int n) 10 { 11 int low = 1; 12 int high = n; 13 int middle, guessOutcome; 14 15 while(low <= high) 16 { 17 middle = low + (high - low) / 2; 18 guessOutcome = guess(middle); 19 20 if(guessOutcome == 1) 21 low = middle + 1; 22 else if(guessOutcome == -1) 23 high = middle - 1; 24 else 25 return middle; 26 } 27 28 return 0; 29 } 30 }
LeetCode 374 Guess Number Higher or Lower
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原文地址：http://www.cnblogs.com/wood-python/p/5837931.html
