Prime factors

.gitignore

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+# CMake
+build*
+cmake-build-*
+meson-build-*
+*.out
+*.exe
+
+# Xcode
+*.xcworkspace
+*.xcodeproj
+
+# Visual Studio
+*.sln
+*.vcxproj
+*.vcxproj.filters
+*.vcxproj.user
+.vs
+
+# Makefile
+Makefile
+*.make
+
+# nvim
+.ccls
+.ccls-cache
+compile_commands.json
+
+# Visual Studio Code
+.vscode
+
+# JetBrains
+.idea
+.fleet
+
+# macOS
+.DS_Store
+.AppleDouble
+.LSOverride
+
+# Cache
+.cache

futureskills/primefactors.cpp

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+#include <cstdio>
+#include <cassert>
+#include <vector>
+
+using prime_vec_t = std::vector<int>;
+
+// https://en.wikipedia.org/wiki/Trial_division
+auto prime_factors(int num) -> prime_vec_t {
+    prime_vec_t primes{};
+    int f = 2;
+    while (num > 1) {
+        if (num % f == 0) {
+            primes.emplace_back(f);
+            num = num / f;
+        } else {
+            f += 1;
+        }
+    }
+    return primes;
+}
+
+auto main([[maybe_unused]]int argc, [[maybe_unused]]char const* argv[]) -> int {
+    auto factors = prime_factors(20);
+    for (auto const& factor : factors) {
+        std::printf("%d, ", factor);
+    }
+    std::printf("\n");
+    return 0;
+}