Find the Losers of the Circular Game

CMakeLists.txt

@@ -240,6 +240,7 @@ add_task(find-the-index-of-the-first-occurrence-in-a-string)
 add_task(find-the-k-beauty-of-a-number)
 add_task(find-the-longest-balanced-substring-of-a-binary-string)
 add_task(find-the-longest-valid-obstacle-course-at-each-position)
+add_task(find-the-losers-of-the-circular-game)
 add_task(find-the-maximum-achievable-number)
 add_task(find-the-maximum-divisibility-score)
 add_task(find-the-maximum-number-of-marked-indices)

solutions/find-the-losers-of-the-circular-game/CMakeLists.txt

@@ -0,0 +1 @@
+add_catch(test_find_the_losers_of_the_circular_game test.cpp)

solutions/find-the-losers-of-the-circular-game/solution.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <vector>
+
+class Solution {
+public:
+  static std::vector<int> circularGameLosers(int n, int k) {
+    std::vector<bool> seen(n);
+    for (int i = 0, steps = k; !seen[i]; i = (i + steps) % n, steps += k) {
+      seen[i] = true;
+    }
+
+    std::vector<int> ans;
+    for (int i = 0; i < n; ++i) {
+      if (!seen[i]) {
+        ans.push_back(i + 1);
+      }
+    }
+    return ans;
+  }
+};

solutions/find-the-losers-of-the-circular-game/test.cpp

@@ -0,0 +1,29 @@
+#include <catch.hpp>
+
+#include <solution.hpp>
+
+TEST_CASE("Simple") {
+  struct TestCase {
+    int n;
+    int k;
+    std::vector<int> expected;
+  };
+
+  std::vector<TestCase> test_cases{
+      {
+          .n = 5,
+          .k = 2,
+          .expected{4, 5},
+      },
+      {
+          .n = 4,
+          .k = 4,
+          .expected{2, 3, 4},
+      },
+  };
+
+  for (const auto &[n, k, expected] : test_cases) {
+    const auto actual = Solution::circularGameLosers(n, k);
+    REQUIRE(expected == actual);
+  }
+}