> ## Documentation Index
> Fetch the complete documentation index at: https://leetcode-py.wisl.dev/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> leetcode-py is a Python LeetCode practice environment generator with one CLI: lcpy. It is not a service or platform.
> Each problem is a directory under leetcode/ with README.md, solution.py, test_solution.py, helpers.py, and playground.ipynb. lcpy gen creates them from JSON templates bundled with the package.
> Examples are backed by tests; copy them verbatim.

# Minimum Size Subarray Sum Python Solution

> Tested Python solution for LeetCode 209 with 15 pytest cases. Generate a practice environment with lcpy.

LeetCode 209, Medium. Topics: Array, Binary Search, Sliding Window, Prefix Sum. [View on LeetCode](https://leetcode.com/problems/minimum-size-subarray-sum/description/).

Generate this problem as a practice environment: tested reference solution, 15 [parametrized pytest cases](/practice/testing), and a playground notebook:

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
lcpy gen -n 209   # by problem number
lcpy gen -s minimum_size_subarray_sum   # by problem name
```

## Problem

Given an array of positive integers `nums` and a positive integer `target`, return *the **minimal length** of a **subarray** whose sum is greater than or equal to* `target`. If there is no such subarray, return `0` instead.

### Examples

```
Input: target = 7, nums = [2,3,1,2,4,3]
Output: 2
Explanation: The subarray [4,3] has the minimal length under the problem constraint.
```

```
Input: target = 4, nums = [1,4,4]
Output: 1
```

```
Input: target = 11, nums = [1,1,1,1,1,1,1,1]
Output: 0
```

### Constraints

* 1 \<= target \<= 10^9
* 1 \<= nums.length \<= 10^5
* 1 \<= nums\[i] \<= 10^4

**Follow up:** If you have figured out the `O(n)` solution, try coding another solution of which the time complexity is `O(n log(n))`.

## Solution

Reference implementation from [solution.py on GitHub](https://github.com/wislertt/leetcode-py/blob/main/leetcode/minimum_size_subarray_sum/solution.py), full suite in [test\_solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/minimum_size_subarray_sum/test_solution.py):

```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
class Solution:
    # Time: O(n)
    # Space: O(1)
    def min_sub_array_len(self, target: int, nums: list[int]) -> int:
        left = 0
        window_sum = 0
        min_len = len(nums) + 1

        for right in range(len(nums)):
            window_sum += nums[right]
            while window_sum >= target:
                min_len = min(min_len, right - left + 1)
                window_sum -= nums[left]
                left += 1

        return 0 if min_len > len(nums) else min_len
```

## Complexity

| Time | Space |
| ---- | ----- |
| O(n) | O(1)  |

## Tags

[NeetCode 250](/catalog/neetcode-250), [NeetCode All](/catalog/neetcode).