Add random example

src/random_example.cc

@@ -0,0 +1,43 @@
+#include "roditty_zwick.h"
+
+#include <random>
+
+int main() {
+  graph::Digraph<std::uint16_t> G;
+  auto gen = std::bind(std::uniform_real_distribution<>(0, 1), 
+                       std::default_random_engine());
+
+  std::vector<std::pair<std::uint16_t, std::uint16_t>> dl_set;
+  std::vector<std::pair<std::uint16_t, std::uint16_t>> qr_set;
+  for (int i = 0; i <= 100; ++i) {
+    for (int j = 0; j <= 100; ++j) {
+      auto rand = gen();
+      if (rand < 0.5) {
+        G.insert(i, j);
+        if (rand < 0.25)
+          dl_set.push_back({ i, j });
+        if (rand < 0.125)
+          qr_set.push_back({ i, j });
+      }
+    }
+  }
+
+  // Initialize the Roditty and Zwick's dynamic reachability algorithm
+  // for general directed graphs inspired by Henzinger and King
+  algo::HenzingerKing<std::uint16_t>* dr = new algo::HenzingerKing(G);
+  dr->init();
+
+  // Remove a random collection of edges from the digraph
+  dr->remove(dl_set);
+
+  // Answer queries using the maintained transitive closure, if the
+  // queried edge has been deleted, insert it into the digraph again
+  for (const auto& q : qr_set) {
+    if (dr->query(q.first, q.second))
+      ;
+    else
+      dr->insert(q.first, q.second);
+  }
+
+  return 0;
+}