Smallest Subarray With a Greater Sum (easy)

Problem Statement

Given an array of positive integers and a 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 greater 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 sum greater than or equal to '7' is [8].

Example 3:

Input: [3, 4, 1, 1, 6], S=8
Output: 3