mzuenni tests

1 files changed, 31 insertions, 0 deletions

diff --git a/content/math/berlekampMassey.cpp b/content/math/berlekampMassey.cpp
new file mode 100644
index 0000000..29e084f
--- /dev/null
+++ b/content/math/berlekampMassey.cpp
@@ -0,0 +1,31 @@
+constexpr ll mod = 1'000'000'007;
+vector<ll> BerlekampMassey(const vector<ll>& s) {
+	int n = sz(s), L = 0, m = 0;
+	vector<ll> C(n), B(n), T;
+	C[0] = B[0] = 1;
+
+	ll b = 1;
+	for (int i = 0; i < n; i++) {
+		m++;
+		ll d = s[i] % mod;
+		for (int j = 1; j <= L; j++) {
+			d = (d + C[j] * s[i - j]) % mod;
+		}
+		if (!d) continue;
+		T = C;
+		ll coef = d * powMod(b, mod-2, mod) % mod;
+		for (int j = m; j < n; j++) {
+			C[j] = (C[j] - coef * B[j - m]) % mod;
+		}
+		if (2 * L > i) continue;
+		L = i + 1 - L;
+		swap(B, T);
+		b = d;
+		m = 0;
+	}
+
+	C.resize(L + 1);
+	C.erase(C.begin());
+	for (auto& x : C) x = (mod - x) % mod;
+	return C;
+}