# Minimum Size Subarray Sum

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:

Example 2:

Example 3:

Constraints:

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

Implementation:

We could keep 2 pointers ,one for the start and another for the end of the current subarray, and make optimal moves so as to keep the sum greater than s as well as maintain the lowest size possible.

Algorithm

• Initialize left pointer to 0 and sum to 0
• Iterate over the nums:
• Add nums[i] to sum.
• While sum is greater than or equal to s:
• Update result=min(result,i+1−left), where i+1−left is the size of current subarray.
• It means that the first index can safely be incremented, since, the minimum subarray starting with this index with sum≥s has been achieved
• Subtract nums[left] from sum and increment left.

Complexity analysis

• Time complexity: O(n). Single iteration .
• Space complexity: O(1) extra space.

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Full Stack Programmer, love to solve problem’s during free time.

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Full Stack Programmer, love to solve problem’s during free time.