Recaman sequenece

recaman.cpp

@@ -0,0 +1,64 @@
+/*
+ * Compile with GCC using "g++ --std=c++23 recaman.cpp -o program""
+ *
+ * SPDX-FileCopyrightText: Dora "cat" <cat@thenight.club>
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public License,
+ * v. 2.0. If a copy of the MPL was not distributed with this file, You can
+ * obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <algorithm>
+#include <cstdint>
+#include <exception>
+#include <iostream>
+#include <print>
+#include <vector>
+
+int main(int argc, char **argv) {
+  if (argc != 2) {
+    std::print(std::cerr, "You must exclusively specify 1 argument as n (MUST "
+                          "be uint64). Terminating.\n");
+    return 1;
+  }
+
+  uint64_t goalN = 0, currentN = 0;
+  try {
+    goalN = std::stoull(argv[1]);
+  } catch (std::exception e) {
+    std::print(std::cerr, "Error: could not convert {} to uint64. Aborting.\n",
+               argv[1]);
+    return 1;
+  }
+
+  std::vector<uint64_t> values(goalN);
+  int64_t expressionResult = 0;
+
+  // Idea is that each Recaman's number is reliant on the number below it, so we
+  // can start from the bottom and generate to the top
+  while (goalN > currentN) {
+    if (currentN == 0) {
+      ++currentN;
+      continue;
+    }
+
+    expressionResult = values[currentN - 1] - currentN;
+    if (expressionResult <= 0 || std::find(values.begin(), values.end(),
+                                           expressionResult) != values.end()) {
+      expressionResult += currentN * 2;
+    }
+
+    values[currentN] = expressionResult;
+    ++currentN;
+  }
+
+  // Once GCC fully implements C++23, I could do
+  // std::print("result: {}\n", values);
+  std::print("result:");
+  for (uint64_t value : values) {
+    std::print(" {} ", value);
+  }
+  std::print("\n");
+  return 0;
+}