Grokking the Coding Interview: Patterns for Coding Questions

Solution: Smallest Subarray With a Greater Sum 

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