209. Minimum Size Subarray Sum

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.

 

Example 1:

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.

Example 2:

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

Example 3:

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

 

Constraints:

• 1 <= target <= 109
• 1 <= nums.length <= 105
• 1 <= nums[i] <= 104

 

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)).

 

---

class Solution:
    def minSubArrayLen(self, target: int, nums: List[int]) -> int:
        ans=len(nums)+1
        total=left=right=0
        for i in range(len(nums)):
            total+=nums[right]
            while total>=target:
                ans=min(ans, right-left+1)
                total-=nums[left]
                left+=1
            right+=1
            
        return ans if sum(nums)>=target else 0