mzuenni tests

1 files changed, 15 insertions, 0 deletions

diff --git a/content/math/transforms/fftMul.cpp b/content/math/transforms/fftMul.cpp
new file mode 100644
index 0000000..660ed79
--- /dev/null
+++ b/content/math/transforms/fftMul.cpp
@@ -0,0 +1,15 @@
+vector<cplx> mul(vector<ll>& a, vector<ll>& b) {
+	int n = 1 << (__lg(sz(a) + sz(b) - 1) + 1);
+	vector<cplx> c(all(a)), d(n);
+	c.resize(n);
+	for (int i = 0; i < sz(b); i++) c[i] = {real(c[i]), b[i]};
+	fft(c);
+	for (int i = 0; i < n; i++) {
+		int j = (n - i) & (n - 1);
+		cplx x = (c[i] + conj(c[j])) / cplx{2, 0}; //fft(a)[i];
+		cplx y = (c[i] - conj(c[j])) / cplx{0, 2}; //fft(b)[i];
+		d[i] = x * y;
+	}
+	fft(d, true);
+	return d;
+}