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I have an array like this in the array,

uint256[] public numberArr= [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];

Each number in an array have their own weight,

uint256[] public weightNumberArr = [1, 3, 9, 7, 15, 18, 36, 22, 12, 6];

Here you can say that the weight of number 0 is 1 and for number 2 it is 3 like that. So here Chance of arriving number 6 is more than a chance of arriving number 0.

How can I generate a random number array of 0 to 9 by using weighted probability in solidity?

Any help will be highly appreciated!

  • Your question seems unrelated to Ethereum, but here is the same question from stackoverflow stackoverflow.com/questions/1761626/weighted-random-numbers. – Ismael Sep 8 at 22:09
  • Thanks for reply @Ismael, I want to know how it can be unrelated to Ethereum, I was asking for it in solidity. Are you saying that this is not possible in solidity? – Mr. Sirja Sep 9 at 5:12
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    I mean the more general questions can be asked in stackoverflow, and there are many more developers there that can help you. Now with the algorithm on hand it should be easy to write in solidity ;) – Ismael Sep 9 at 13:58
  • Thanks @Ismael for you kind reply, really appreciate that. Btw I figured that out and followed the same way you said. Thanks brother! – Mr. Sirja Sep 10 at 7:13
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As hinted at by Ismael in the comments your question is mostly about the algorithm and is largely answered in the linked stackoverflow question.

However the part which is special for Solidity (and Ethereum) is the randomness part. Randomness in deterministic smart contracts is a tough question - there are good and bad solutions for it.

So once you decide on how to get your random number the rest is accomplished by simply implementing the given algorithm in Solidity. The only problematic part will be gas limits if there are too many numbers - iterating over the items may result in out of gas exceptions. In that case you have to find a different algorithm.

  • Thanks for detailed explanation, I really appreciate this. Just came up with the algorithm which consumes no gas and will work seamlessly even if there are too many numbers. – Mr. Sirja Sep 10 at 8:43

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