209. Minimum Size Subarray Sum

Medium

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Given an array of positive integers nums and a positive integer target, return the minimal length of a contiguous subarray [numsl, numsl+1, ..., numsr-1, numsr] of which the 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] <= 105

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:
        start = index = 0
        total = 0
        result = len(nums)*2 # Dummy Value
        while index < len(nums):
            total += nums[index]
            while total >= target and start < len(nums):
                result = min(result, (index-start+1))
                total -= nums[start]
                start+=1
            index += 1
        return 0 if result == len(nums)*2 else result