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LeetCode 209 Minimum Size Subarray Sum - Medium

209. Minimum Size Subarray Sum

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209. Minimum Size Subarray Sum — Medium

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Problem

  1. Minimum Size Subarray Sum

Given an array of n positive integers and a positive integer s, find the minimal length of a contiguous subarray of which the sum ≥ s. If there isn't one, return 0 instead.

Example:

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

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

# 同向双指针 模板题：
 
class Solution:
    def minSubArrayLen(self, s: int, nums: List[int]) -> int:
        if not nums:
            return 0
        right = 0
        SUM = 0
        res = float('inf')
        for left in range(len(nums)):
            while right < len(nums) and SUM < s:
                SUM += nums[right]
                right += 1
            if SUM >= s:
                res = min(res, right - left)
            SUM -= nums[left]
        if res == float('inf'):
            return 0
        return res

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