Restructure into python package

[cheran-senthil]

Perhaps we can add namespace for some of the functions like fft, ntt instead of directly calling.

[Mukundan314]

Problems

Problem

cumsum2d uses global vars

Possible Solutions

• Convert it into a class

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Problem

nCr_p does pre-computations based on mod this makes changing the mod not possible

Possible Solutions

• Convert it into a class
• Add function to change the mod

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Problem

Hashing class uses global mod.

Possible Solutions

• Store mod inside class

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Problem

ntt contains global vars dependent on the mod

Possible Solutions

• Add function to change the mod

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Problem

Modular import is not possible

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