new file: algo/fibonacci.go

README.md

@@ -31,7 +31,7 @@
 
 - [x] Kadane's Algorithm
 - [x] Euclidean gcd
-- [ ] Fibonacci
+- [x] Fibonacci
 - [ ] Modular Arithmetic
 - [ ] Sieve of Eratosthenes
 - [ ] BFS Breadth-First Search

algo/fibonacci.go

@@ -0,0 +1,16 @@
+package algo
+
+// Fib() -> fibonacci linear implementation O(n)
+func Fib(target int) int {
+	a := 0
+	b := 1
+
+	if target <= 1 {
+		return target
+	}
+
+	for a < target {
+		a, b = b, a+b
+	}
+	return a
+}