# 35. 搜索插入位置

<https://leetcode-cn.com/problems/search-insert-position/>

* [35. 搜索插入位置](https://suki.gitbook.io/91-days-algorithm/basic/two-pointers/pages/-MNWDoo5X0cWyh0BFebd#35-搜索插入位置)
  * [题目描述](https://suki.gitbook.io/91-days-algorithm/basic/two-pointers/pages/-MNWDoo5X0cWyh0BFebd#题目描述)
  * [方法 1：二分查找](https://suki.gitbook.io/91-days-algorithm/basic/two-pointers/pages/-MNWDoo5X0cWyh0BFebd#方法-1二分查找)
    * [思路](https://suki.gitbook.io/91-days-algorithm/basic/two-pointers/pages/-MNWDoo5X0cWyh0BFebd#思路)
    * [复杂度分析](https://suki.gitbook.io/91-days-algorithm/basic/two-pointers/pages/-MNWDoo5X0cWyh0BFebd#复杂度分析)
    * [代码](https://suki.gitbook.io/91-days-algorithm/basic/two-pointers/pages/-MNWDoo5X0cWyh0BFebd#代码)

## 题目描述

```
给定一个排序数组和一个目标值，在数组中找到目标值，并返回其索引。如果目标值不存在于数组中，返回它将会被按顺序插入的位置。

你可以假设数组中无重复元素。

示例 1:

输入: [1,3,5,6], 5
输出: 2
示例 2:

输入: [1,3,5,6], 2
输出: 1
示例 3:

输入: [1,3,5,6], 7
输出: 4
示例 4:

输入: [1,3,5,6], 0
输出: 0

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/search-insert-position
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
```

## 方法 1：二分查找

### 思路

用二分法找到目标值，或者找到大于目标值的数字中最左边的那个，返回下标。

### 复杂度分析

* 时间复杂度：$O(logN)$，N 是数组长度。
* 空间复杂度：$O(1)$。

### 代码

JavaScript Code

```javascript
/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number}
 */
var searchInsert = function (nums, target) {
    let l = 0,
        r = nums.length - 1,
        mid = 0;

    while (l <= r) {
        mid = ((r - l) / 2 + l) << 0;
        if (nums[mid] < target) l = mid + 1;
        else if (nums[mid] > target) r = mid - 1;
        else return mid;
    }

    return l;
};
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://suki.gitbook.io/91-days-algorithm/basic/two-pointers/25.search-insert-position.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.