Given an array of positive numbers and a positive number S, find
the length of the smallest contiguous subarray whose sum is greater
than or equal to S. Return 0, if no such subarray exists.
Example 1
Input: [2, 1, 5, 2, 3, 2], S=7 Output: 2 Explanation: The
smallest subarray with a sum great than or equal to '7' is [5,
2].
Example 2
Input: [2, 1, 5, 2, 8], S=7 Output: 1 Explanation: The smallest
subarray with a...