ChatGPT made a mistake with calculating Big O


You’re correct that if the number of characters (numChars) is treated as a constant, the complexity simplifies accordingly.

Simplified Complexity

When considering numChars as a constant (e.g., 26 for the English alphabet), the time complexity can be analyzed differently:

  1. Constant Factor:
  • If numChars is constant, we can denote it as CCC. Thus, the complexity of the recursive calls would be O(Cn)O(C^n)O(Cn).
  1. Final Complexity:
  • When CCC is constant, CnC^nCn behaves like an exponential growth function in terms of n. Therefore, in this context, the complexity can be expressed as O(1)⋅O(nn)O(1) \cdot O(n^n)O(1)⋅O(nn) or simply O(nn)O(n^n)O(nn) for very large n.

Overall Time Complexity

Therefore, when considering numChars as constant, the complexity simplifies to:

O(nn)O(n^n)O(nn)

This indicates that the time grows polynomially with respect to the length of the strings being generated.

Conclusion

In summary, when numChars is constant, we can reduce the complexity to a more manageable form, and it becomes clear that the recursive nature still causes an exponential increase in calls with respect to n. This emphasizes the efficiency concerns when n grows large.

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