"You should compute P⋅Q−1 modulo 109+7, where Q−1 denotes the multiplicative inverse of Q modulo 109+7."↵
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So, I more (or less) understood what that means.↵
I can express, say 1/5 by the number 400000003.↵
I can calculate that number using https://www.geeksforgeeks.org/fermats-little-theorem/ implemented by some code I found somewhere (see below).↵
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BUT: How do I add (and/or multiply) fractions with huge values?↵
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i.e. how to calculate and express something like this:↵
Let E=10e9+7↵
Then, how to express: ((E+1) / (E+2)) + ((E+3) / (E+4))↵
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Any hint or link to an understandable explenation would be really helpfull.↵
Thanks. ↵
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The code I use so far, based on that fermat thing:↵
class Inv {↵
companion object {↵
val defaultMod = 1000000007L↵
var MOD = defaultMod↵
↵
fun toPower(a: Long, p: Long, mod: Long = MOD): Long {↵
var a = a↵
var p = p↵
var res = 1L↵
while (p != 0L) {↵
if (p and 1 == 1L)↵
res = res * a % mod↵
p = p shr 1↵
a = a * a % mod↵
}↵
return res↵
}↵
↵
fun inv(x: Long, mod: Long = MOD): Long {↵
return toPower(x, mod - 2)↵
}↵
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fun simpleInf(nenner: Long, zaehler: Long): Long {↵
return nenner * Inv.inv(zaehler) % Inv.MOD↵
}↵
}↵
}↵
↵
