Fermat_Little_Theorem.jl

# Finding greatest common divisor using Euclidean Algorithm
function gcdFunction(a, b)
    if a == 0
        return b
    end
    return gcdFunction(b % a, a)
end
function power(x, y, m)
    if y == 0
        return 1
    end
    p = power(x, y / 2, m) % m
    p = (p * p) % m

    if y % 2 == 0
        return p
    else
        return (x * p) % m
    end
end
function modInverse(a, m)
    gcd = gcdFunction(a, m)

    if gcd != 1
        return -1
    else
        return power(a, m - 2, m)
    end
end

a = 3
m = 11

ans = modInverse(a, m)

if ans == -1
    println("Inverse doesn't exist")
else
    println("Modular multiplicative inverse is $(ans-1)")
end

# Output

#Modular multiplicative inverse is 4