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-rw-r--r--math/modExp.cpp16
-rw-r--r--math/primes.cpp7
2 files changed, 7 insertions, 16 deletions
diff --git a/math/modExp.cpp b/math/modExp.cpp
index 967068c..d74eca0 100644
--- a/math/modExp.cpp
+++ b/math/modExp.cpp
@@ -1,15 +1,7 @@
// Laufzeit: O(log(b))
-ll multMod(ll a, ll b, ll n) {
- if(a == 0 || b == 0) return 0;
- if(b == 1) return a % n;
- if(b % 2 == 1) return (a + multMod(a, b-1, n)) % n;
- else return multMod((a + a) % n, b / 2, n);
-}
-
-// Laufzeit: O(log(b))
ll powMod(ll a, ll b, ll n) {
- if(b == 0) return 1;
- if(b == 1) return a % n;
- if(b % 2 == 1) return multMod(powMod(a, b-1, n), a, n);
- else return powMod(multMod(a, a, n), b / 2, n);
+ if(b == 0) return 1;
+ if(b == 1) return a % n;
+ if(b & 1) return (powMod(a, b - 1, n) * a) % n;
+ else return powMod((a * a) % n, b / 2, n);
}
diff --git a/math/primes.cpp b/math/primes.cpp
index 1694f6a..bbc63d9 100644
--- a/math/primes.cpp
+++ b/math/primes.cpp
@@ -7,7 +7,7 @@ bool isPrime(ll n) { // Miller Rabin Primzahltest. O(log n)
ll v = powMod(a, d, n); // Implementierung von oben.
if(v == 1 || v == n - 1) continue;
for(int i = 1; i <= j; i++) {
- v = multMod(v, v, n); // Implementierung von oben.
+ v = (v * v) % n;
if(v == n - 1 || v <= 1) break;
}
if(v != n - 1) return false;
@@ -19,9 +19,8 @@ ll rho(ll n) { // Findet Faktor < n, nicht unbedingt prim.
if (~n & 1) return 2;
ll c = rand() % n, x = rand() % n, y = x, d = 1;
while (d == 1) {
- x = (multMod(x, x, n) + c) % n;
- y = (multMod(y, y, n) + c) % n;
- y = (multMod(y, y, n) + c) % n;
+ x = ((x * x) % n + c) % n;
+ y = ((y * y) % n + c) % n;
d = gcd(abs(x - y), n); // Implementierung von oben.
}
return d == n ? rho(n) : d;