Day029 - 209. Minimum Size Subarray Sum

209. Minimum Size Subarray Sum

Given an array of positive integers nums and a positive integer target, return the minimal length of a subarray (A subarray is a contiguous non-empty sequence of elements within an array.) 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)).

내 풀이

class Solution:
    def minSubArrayLen(self, target: int, nums: List[int]) -> int:
        if sum(nums) < target: return 0
        elif sum(nums) == target : return len(nums)

        l = 0
        max_val = 0
        min_len = len(nums)

        for r in range(len(nums)):
            max_val += nums[r]
            
            while max_val >= target:
                min_len = min(min_len, r-l+1)
                max_val -= nums[l]
                l += 1

        return min_len

# Time Complexity : \(O(N)\)