Is there any limit to the length of the string after which hashing should be avoided. Also can the hashing solutions be easily hacked in contests ?
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According to the birthday paradox, if m = 1e9 + 9, we can random about 200000 strings and the possibility of collisions is more than 99.9999%!
Simple code can calculate the possibility:
Also, if you want to make your hashing become hard to hack, there are two possible choice:
use a long long prime as m
use two or more hash functions
Sorry for my poor English, I hope this can help you:)
Well, that might make it a bit harder to hack, but still hackable. You should also make your base randomized.