🟢 Port problem 412 (Fizz Buzz) from Clojure/Ruby to C++23

solutions/0401-0500/0412-fizz-buzz/README.md

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+# 412. Fizz Buzz
+
+[LeetCode problem 412](https://leetcode.com/problems/fizz-buzz/)
+
+- **Difficulty**: Easy
+- **Tags**: math, string, simulation
+
+## Description
+
+Given an integer `n`, return a string array `answer` (1-indexed) where:
+
+- `answer[i] == "FizzBuzz"` if `i` is divisible by 3 and 5.
+- `answer[i] == "Fizz"` if `i` is divisible by 3.
+- `answer[i] == "Buzz"` if `i` is divisible by 5.
+- `answer[i] == i` (as a string) otherwise.

solutions/0401-0500/0412-fizz-buzz/solution.cpp

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+#include "solution.hpp"
+
+namespace leetcode::p0412 {
+
+std::vector<std::string> solve(int n) {
+    std::vector<std::string> result;
+    result.reserve(static_cast<std::size_t>(n));
+
+    for (int i = 1; i <= n; ++i) {
+        if (i % 15 == 0) {
+            result.emplace_back("FizzBuzz");
+        } else if (i % 3 == 0) {
+            result.emplace_back("Fizz");
+        } else if (i % 5 == 0) {
+            result.emplace_back("Buzz");
+        } else {
+            result.push_back(std::to_string(i));
+        }
+    }
+
+    return result;
+}
+
+} // namespace leetcode::p0412

solutions/0401-0500/0412-fizz-buzz/solution.hpp

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+#pragma once
+
+#include <string>
+#include <vector>
+
+namespace leetcode::p0412 {
+
+// optimized: O(n) time, O(n) space (excluding the output) — one pass.
+std::vector<std::string> solve(int n);
+
+} // namespace leetcode::p0412

solutions/0401-0500/0412-fizz-buzz/test.cpp

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+#include <catch2/catch_test_macros.hpp>
+
+#include "solution.hpp"
+
+TEST_CASE("Problem 412", "[p0412]") {
+    CHECK(leetcode::p0412::solve(1) == std::vector<std::string>{"1"});
+    CHECK(leetcode::p0412::solve(3) == std::vector<std::string>{"1", "2", "Fizz"});
+    CHECK(leetcode::p0412::solve(5) == std::vector<std::string>{"1", "2", "Fizz", "4", "Buzz"});
+    CHECK(leetcode::p0412::solve(15) == std::vector<std::string>{
+                                            "1",
+                                            "2",
+                                            "Fizz",
+                                            "4",
+                                            "Buzz",
+                                            "Fizz",
+                                            "7",
+                                            "8",
+                                            "Fizz",
+                                            "Buzz",
+                                            "11",
+                                            "Fizz",
+                                            "13",
+                                            "14",
+                                            "FizzBuzz",
+                                        });
+}