209. Minimum Size Subarray Sum

• categories: Code, Interview Question, leetcode, Medium
• source: https://leetcode.com/problems/minimum-size-subarray-sum/
• topics: Sliding Window

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.

class Solution:
    def minSubArrayLen(self, target: int, nums: List[int]) -> int:
        window_sum = 0
        ans = float('inf')
        current_window_size = 0
 
        for i in range(len(nums)):
            window_sum += nums[i]
            current_window_size += 1
            while window_sum >= target:
                current_window_size -= 1
                ans = min(ans, current_window_size + 1)
                window_sum -= nums[i - current_window_size]
            
        return ans if ans < float('inf') else 0