# 374. Guess Number Higher or Lower 猜数字大小

@TOC

## # 题目描述

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.
``````

## # 解题方法

``````/* 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 low = 1;
int high = n;
int mid = 0;
while(low <= high){
mid = low + (high - low) / 2;
if(guess(mid) == -1){
high = mid - 1;
}else if(guess(mid) == 1){
low = mid + 1;
}else{
return mid;
}
}
return mid;
}
}
``````

python解法如下：

``````# The guess API is already defined for you.
# @param num, your guess
# @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
# def guess(num):

class Solution(object):
def guessNumber(self, n):
"""
:type n: int
:rtype: int
"""
left, right = 1, n #[left, right]
mid = left
while left <= right:
mid = (right + left) / 2
res = guess(mid)
if res == 0:
return mid
elif res == 1:
left = mid + 1
else:
right = mid - 1
return mid
``````

## # 日期

2017 年 5 月 10 日 2018 年 11 月 23 日 —— 这就星期五了？？