Given an array of **positive** integers `nums` and a positive integer `target`, return the **minimal length** of a contiguous 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
Explanation:The whole array sums to 8 < 11, so no valid subarray exists.