Inital code commit

Author: T-PWK

fib.go

@@ -0,0 +1,38 @@
+package fib
+
+import "math/big"
+
+// Fibonacci calculates Fibonacci number.
+// This function generated correct values from 0 to 93 sequence number.
+// For bigger values use FibonacciBig function
+func Fibonacci(n uint) uint64 {
+	if n <= 1 {
+		return uint64(n)
+	}
+
+	var n2, n1 uint64 = 0, 1
+
+	for i := uint(2); i < n; i++ {
+		n2, n1 = n1, n1+n2
+	}
+
+	return n2 + n1
+}
+
+// FibonacciBig calculates Fibonacci number using bit.Int.
+// For the sequence numbers below 94, it is recommended to use Fibonacci function.
+func FibonacciBig(n uint) *big.Int {
+	if n <= 1 {
+		return big.NewInt(int64(n))
+	}
+
+	var n2, n1, tmp = big.NewInt(0), big.NewInt(1), big.NewInt(0)
+
+	for i := uint(1); i < n; i++ {
+		tmp.Set(n1)
+		n1.Add(n1, n2)
+		n2.Set(tmp)
+	}
+
+	return n1
+}

fib_test.go

@@ -0,0 +1,57 @@
+package fib
+
+import "testing"
+
+func BenchmarkFibonacci_10(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Fibonacci(10)
+	}
+}
+
+func BenchmarkFibonacci_20(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Fibonacci(20)
+	}
+}
+
+func BenchmarkFibonacciBig_10(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FibonacciBig(10)
+	}
+}
+
+func BenchmarkFibonacciBig_20(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FibonacciBig(20)
+	}
+}
+
+func TestFibonacci(t *testing.T) {
+	data := []struct {
+		n    uint
+		want uint64
+	}{
+		{0, 0}, {1, 1}, {2, 1}, {3, 2}, {4, 3}, {5, 5}, {6, 8}, {10, 55}, {42, 267914296},
+	}
+
+	for _, d := range data {
+		if got := Fibonacci(d.n); got != d.want {
+			t.Errorf("Invalid Fibonacci value for N: %d, got: %d, want: %d", d.n, got, d.want)
+		}
+	}
+}
+
+func TestFibonacciBig(t *testing.T) {
+	data := []struct {
+		n    uint
+		want int64
+	}{
+		{0, 0}, {1, 1}, {2, 1}, {3, 2}, {4, 3}, {5, 5}, {6, 8}, {10, 55}, {42, 267914296},
+	}
+
+	for _, d := range data {
+		if got := FibonacciBig(d.n); got.Int64() != d.want {
+			t.Errorf("Invalid Fibonacci value for N: %d, got: %d, want: %d", d.n, got, d.want)
+		}
+	}
+}