test: add standalone radix sort test file

Author: a1fredbao

verify/verify-standalone-algorithm/standalone-radix-sort.test.cpp

@@ -0,0 +1,21 @@
+// competitive-verifier: STANDALONE
+
+#include "../../src/alfred/algorithm/radix-sort.hpp"
+#include <cassert>
+#include <random>
+
+const int N = 100000000;
+
+uint32_t a[N];
+std::mt19937 rng(std::random_device{}());
+
+int main(int argc, char const *argv[]) {
+    for (int i = 0; i < N; i++) {
+        a[i] = rng();
+    }
+    radix_sort(a, N);
+    for (int i = 1; i < N; i++) {
+        assert(a[i - 1] <= a[i]);
+    }
+    return 0;
+}