stringPermutations function has exponential time complexity causing severe performance degradation

[Shree-Gowda]

Description:
The current stringPermutations function uses a recursive approach with exponential time complexity O(n!). For a 10-character string, it takes ~2 seconds to complete, which is unacceptable for production use.

Current Implementation Problems:

1. Exponential Time Complexity: O(n!) - For n=10, that's 3,628,800 operations
2. Memory Inefficiency: Uses Set to store all permutations in memory
3. No Early Termination: Cannot limit the number of permutations generated
4. Recursive Stack Overflow Risk: Deep recursion for large strings

Performance Impact:

• 10 characters: ~2 seconds
• 11 characters: ~22 seconds (estimated)
• 12 characters: ~4+ minutes (estimated)

Proposed Solutions:

1. Iterative Implementation: Replace recursion with iteration
2. Generator Pattern: Return permutations on-demand instead of all at once
3. Early Termination: Add optional limit parameter
4. Memory Optimization: Use more efficient data structures

[SHAKSHIY]

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