**Problem Statement:**
Given the required input arguments, write an efficient algorithm to solve the **Partition Labels** problem. Implement the required logic as specified by standard definitions for this classic algorithmic challenge.
**Hint / Expected Approach:**
Last occurrence map; track current partition end
**Edge Cases to Consider:**
- (1) All same characters (one partition)
- (2) All unique characters (n partitions)
- (3) Nested ranges