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Algorithms

Given an array of integers <code>nums</code> which is sorted in ascending order, and an integer <code>target</code>, write a function to search <code>target</code> in <code>nums</code>. If <code>target</code> exists, then return its index. Otherwise, return <code>-1</code>.

You must write an algorithm with <code>O(log n)</code> runtime complexity.

&nbsp;
Example 1:

<pre>
Input: nums = [-1,0,3,5,9,12], target = 9
Output: 4
Explanation: 9 exists in nums and its index is 4
</pre>

Example 2:

<pre>
Input: nums = [-1,0,3,5,9,12], target = 2
Output: -1
Explanation: 2 does not exist in nums so return -1
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= nums.length &lt;= 104</code></li>
	<li><code>-104 &lt; nums[i], target &lt; 104</code></li>
	<li>All the integers in <code>nums</code> are unique.</li>
	<li><code>nums</code> is sorted in ascending order.</li>
</ul>

search

Binary Search

Search in a Sorted Array of Unknown Size

search-in-a-sorted-array-of-unknown-size

搜索长度未知的有序数组

Maximum Count of Positive Integer and Negative Integer

maximum-count-of-positive-integer-and-negative-integer

正整数和负整数的最大计数

Array

给定一个&nbsp;<code>n</code>&nbsp;个元素有序的（升序）整型数组&nbsp;<code>nums</code> 和一个目标值&nbsp;<code>target</code> &nbsp;，写一个函数搜索&nbsp;<code>nums</code>&nbsp;中的 <code>target</code>，如果目标值存在返回下标，否则返回 <code>-1</code>。

 
示例 1:

<pre>输入: <code>nums</code> = [-1,0,3,5,9,12], <code>target</code> = 9
输出: 4
解释: 9 出现在 <code>nums</code> 中并且下标为 4
</pre>

示例&nbsp;2:

<pre>输入: <code>nums</code> = [-1,0,3,5,9,12], <code>target</code> = 2
输出: -1
解释: 2 不存在 <code>nums</code> 中因此返回 -1
</pre>

&nbsp;

提示：

<ol>
	<li>你可以假设 <code>nums</code>&nbsp;中的所有元素是不重复的。</li>
	<li><code>n</code>&nbsp;将在&nbsp;<code>[1, 10000]</code>之间。</li>
	<li><code>nums</code>&nbsp;的每个元素都将在&nbsp;<code>[-9999, 9999]</code>之间。</li>
</ol>