diff options
| -rwxr-xr-x | test | 10 | ||||
| -rw-r--r-- | zmodn.h | 8 |
2 files changed, 3 insertions, 15 deletions
| @@ -141,16 +141,6 @@ public: | |||
| 141 | assert_equal(p, 92); | 141 | assert_equal(p, 92); |
| 142 | } | 142 | } |
| 143 | }, | 143 | }, |
| 144 | { | ||
| 145 | .name = "4 / 2 mod 6", | ||
| 146 | .f = []() { | ||
| 147 | Zmod<6> four = 4; | ||
| 148 | Zmod<6> two = 2; | ||
| 149 | auto d = four / two; | ||
| 150 | assert_equal(d.has_value(), true); | ||
| 151 | assert_equal(d.value(), 2); | ||
| 152 | } | ||
| 153 | }, | ||
| 154 | }; | 144 | }; |
| 155 | 145 | ||
| 156 | int main() { | 146 | int main() { |
| @@ -40,15 +40,13 @@ public: | |||
| 40 | bool operator!=(const Zmod& z) const { return value != z.value; } | 40 | bool operator!=(const Zmod& z) const { return value != z.value; } |
| 41 | 41 | ||
| 42 | std::optional<Zmod> inverse() const { | 42 | std::optional<Zmod> inverse() const { |
| 43 | auto [g, a, b] = extended_gcd(value, N); | 43 | auto [g, a, _] = extended_gcd(value, N); |
| 44 | return g == 1 ? Zmod(a) : std::optional<Zmod>{}; | 44 | return g == 1 ? Zmod(a) : std::optional<Zmod>{}; |
| 45 | } | 45 | } |
| 46 | 46 | ||
| 47 | std::optional<Zmod> operator/(const Zmod& d) const { | 47 | std::optional<Zmod> operator/(const Zmod& d) const { |
| 48 | auto [g, x, y] = extended_gcd(value, d.toint()); | 48 | auto i = d.inverse(); |
| 49 | auto [a, b] = std::pair<Zmod, Zmod>{value / g, d.toint() / g}; | 49 | return i ? (*this) * i.value() : i; |
| 50 | auto i = b.inverse(); | ||
| 51 | return i ? a * i.value() : i; | ||
| 52 | } | 50 | } |
| 53 | 51 | ||
| 54 | std::optional<Zmod> operator/=(const Zmod& d) { | 52 | std::optional<Zmod> operator/=(const Zmod& d) { |
