mirror of
https://github.com/TheAlgorithms/JavaScript.git
synced 2025-07-19 01:55:51 +08:00
32 lines
775 B
JavaScript
32 lines
775 B
JavaScript
/*
|
|
Modified from:
|
|
https://github.com/TheAlgorithms/Python/blob/master/maths/binary_exp_mod.py
|
|
|
|
Explaination:
|
|
https://en.wikipedia.org/wiki/Exponentiation_by_squaring
|
|
*/
|
|
|
|
const modularBinaryExponentiation = (a, n, m) => {
|
|
// input: a: int, n: int, m: int
|
|
// returns: (a^n) % m: int
|
|
if (n === 0) {
|
|
return 1
|
|
} else if (n % 2 === 1) {
|
|
return (modularBinaryExponentiation(a, n - 1, m) * a) % m
|
|
} else {
|
|
const b = modularBinaryExponentiation(a, n / 2, m)
|
|
return (b * b) % m
|
|
}
|
|
}
|
|
|
|
const main = () => {
|
|
// binary_exponentiation(2, 10, 17)
|
|
// > 4
|
|
console.log(modularBinaryExponentiation(2, 10, 17))
|
|
// binary_exponentiation(3, 9, 12)
|
|
// > 3
|
|
console.log(modularBinaryExponentiation(3, 9, 12))
|
|
}
|
|
|
|
main()
|