Why we have this:
This algorithm here directly follow the rule of ratio to win, and easier to understand.
Just think about a smaller space, e.g. 100, instead of 2^256.
When one miner has 10% power, it should have 10% ratio to win. that is, when the h is in {0..9}, it wins. Simply speaking, it is:
(h + 1) / 100 <= 10% , instead of
h / 99 < 10%
The former is easier to understand, though both are equivalent when h is an integer and power_ratio < 1)
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