Add iterative nth Fibonacci finder

oboukli · Mar 7, 2024 · e04ba81 · e04ba81
1 parent 6d07986
commit e04ba81
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Showing 3 changed files with 41 additions and 13 deletions.
diff --git a/benchmark/fibonacci_benchmark.cpp b/benchmark/fibonacci_benchmark.cpp
@@ -25,10 +25,19 @@ TEST_CASE("fibonacci benchmarking", "[benchmark][fibonacci]")
         .title("Fibonacci number")
         .relative(true)
 
+        .run(
+            NAMEOF_RAW(iterative::fib<std::uint_fast32_t>).c_str(),
+            []() {
+                auto const r{iterative::fib(n)};
+
+                ankerl::nanobench::doNotOptimizeAway(r);
+            })
+
         .run(
             NAMEOF_RAW(recursive::fib<std::uint_fast32_t>).c_str(),
             []() {
-                auto r{recursive::fib(n)};
+                auto const r{recursive::fib(n)};
+
                 ankerl::nanobench::doNotOptimizeAway(r);
             })
 

diff --git a/include/forfun/fibonacci.hpp b/include/forfun/fibonacci.hpp
@@ -15,6 +15,27 @@
 
 namespace forfun::fibonacci {
 
+namespace iterative {
+
+template <typename T>
+    requires std::integral<T>
+    and std::is_same_v<T, decltype(std::declval<T>() + std::declval<T>())>
+[[nodiscard]] constexpr inline T fib(T const n) noexcept
+{
+    T a{0};
+
+    for (T i{0}, b{1}; i < n; ++i)
+    {
+        T const c{a + b};
+        a = b;
+        b = c;
+    }
+
+    return a;
+}
+
+} // namespace iterative
+
 namespace recursive {
 
 template <typename T>

diff --git a/test/fibonacci_test.cpp b/test/fibonacci_test.cpp
@@ -4,37 +4,35 @@
 
 // SPDX-License-Identifier: MIT
 
+#include <catch2/catch_template_test_macros.hpp>
 #include <catch2/catch_test_macros.hpp>
 
 #include "forfun/fibonacci.hpp"
 
-TEST_CASE("Find Fibonacci number", "[fibonacci]")
+TEMPLATE_TEST_CASE_SIG(
+    "Find Fibonacci number",
+    "[fibonacci]",
+    ((auto fib), fib),
+    (forfun::fibonacci::iterative::fib<int>),
+    (forfun::fibonacci::recursive::fib<int>))
 {
-    using forfun::fibonacci::recursive::fib;
-
     SECTION("Negative value case (n = -1)")
     {
-        constexpr auto const n{-1};
-
-        CAPTURE(n);
+        static constexpr int const n{-1};
 
         STATIC_REQUIRE(fib(n) == 0);
     }
 
     SECTION("First (zeroth) Fibonacci number (n = 0) is zero")
     {
-        constexpr auto const n{0};
-
-        CAPTURE(n);
+        static constexpr int const n{0};
 
         STATIC_REQUIRE(fib(n) == 0);
     }
 
     SECTION("Second Fibonacci number (n = 1) is one")
     {
-        constexpr auto const n{1};
-
-        CAPTURE(n);
+        static constexpr int const n{1};
 
         STATIC_REQUIRE(fib(n) == 1);
     }