# 153. Find Minimum in Rotated Sorted Array

## 1.問題

![](https://901207480-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LGKoChvN9am4__HCIRK%2F-Lac-vyvVXWLe4LgCZhw%2F-Lac08BtfdBt8ikBix3n%2Fimage.png?alt=media\&token=852a4921-75a3-4292-ae83-9d5c8a864f9e)

## 2.想法 

* 提問:
* function header, parameter
* test input
* 說明想法 
  * 用binary search
  * 如果left < mid, 表示左半邊已排序-> 左半邊的不看, mid = left
  * 如果left > mid, 表示右半邊未排序-> 右半邊的不看, mid = right

## 3.程式碼

* while loop

```
class Solution {
public:
    int findMin(vector<int>& nums) {
        if (nums.size() == 0) {
            return 0;
        }
        
        int size = nums.size(), left = 0, right = size - 1;
        if (nums[left] > nums[right]) {
            while (left != (right - 1)) {
                int mid = (left + right) / 2;
                if (nums[left] < nums[mid]) {
                    left = mid;
                } else {
                    right = mid;
                }
            }
            return min(nums[left], nums[right]);
        }
        return nums[0];
    }
};
```

* recursive

```
class Solution {
public:
    int findMin(vector<int>& nums) {
        if (nums.empty()) return 0;
        return search(nums, nums[0], 0, nums.size() - 1);
    }
private:
    int search(vector<int>& nums, int res, int left, int right) {
        if (left < right - 1) {
            int mid = (left + right) / 2;
            if (nums[left] < nums[mid]) {
                res = min(res, nums[left]);
                return search(nums, res, mid, right);
            } else {
                res = min(res, nums[right]);
                return search(nums, res, left, mid);
            }
        }
        res = min(res, nums[left]);
        res = min(res, nums[right]);
        return res;
    }
};
```


---

# 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://jenhsuan.gitbook.io/algorithm/leetcode/153.-find-minimum-in-rotated-sorted-array.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.