Guess Number Higher or Lower && 九章二分法模板

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.

Show Company Tags

Show Tags

Show Similar Problems

binary search

/* 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 start = 1;
int end = n;
int res;
while(start<end)
{
int mid = start + (end-start)/2;
if(guess(mid)==0)
{
return mid;
}
else if(guess(mid)==-1)
{
end = mid-1;
}
else
{
start = mid+1;
}
}
if(guess(start)==0) return start;
return end;

}
}

九章二分法模板

主页
课程
讲座
问答
面经
LeetCode答案
FAQ
注册 登录
Binary Search    当前位置 首页 LeetCode 答案查询 / LintCode 答案查询  查看详情 http://www.lintcode.com/problem/binary-search/ 
Binary search is a famous question in algorithm. For a given sorted array (ascending order) and a target number, find the first index of this number in O(log n) time complexity. If the target number does not exist in the array, return -1. Example If the array is [1, 2, 3, 3, 4, 5, 10], for given target 3, return 2.
Java
C++
Python
/**
* 本代码由九章算法编辑提供。没有版权欢迎转发。
* - 九章算法致力于帮助更多中国人找到好的工作，教师团队均来自硅谷和国内的一线大公司在职工程师。
* - 现有的面试培训课程包括：九章算法班，系统设计班，九章强化班，Java入门与基础算法班，
* - 更多详情请见官方网站：http://www.jiuzhang.com/
*/

// version 1: with jiuzhang template
public class Solution {
/**
* @param A an integer array sorted in ascending order
* @param target an integer
* @return an integer
*/
public int findPosition(int[] nums, int target) {
if (nums == null || nums.length == 0) {
return -1;
}

int start = 0, end = nums.length - 1;
while (start + 1 < end) {
int mid = start + (end - start) / 2;
if (nums[mid] == target) {
return mid;
} else if (nums[mid] < target) {
start = mid;
} else {
end = mid;
}
}

if (nums[start] == target) {
return start;
}
if (nums[end] == target) {
return end;
}
return -1;
}
}

// version 2: without jiuzhang template
public class Solution {
/**
* @param A an integer array sorted in ascending order
* @param target an integer
* @return an integer
*/
public int findPosition(int[] nums, int target) {
if (nums == null || nums.length == 0) {
return -1;
}

int start = 0, end = nums.length - 1;
while (start < end) {
int mid = start + (end - start) / 2;
if (nums[mid] == target) {
return mid;
} else if (nums[mid] < target) {
start = mid + 1;
} else {
end = mid - 1;
}
}

if (nums[start] == target) {
return start;
}
return -1;
}
}

© Jiu Zhang 2013-2016. All rights reserved.