working on memoization

vis/include/geometry.hpp

@@ -0,0 +1,38 @@
+#pragma once
+
+#include <tc/core.hpp>
+#include <optional>
+#include <cmath>
+
+size_t key(const std::vector<int> &gens) {
+    size_t bits = 0;
+    for (const auto &gen : gens) {
+        bits |= 1U << gen;
+    }
+    return bits;
+}
+
+struct CosetMemo {
+    const tc::Group &parent;
+    std::vector<std::vector<std::optional<tc::Cosets>>> results;
+
+    explicit CosetMemo(const tc::Group &parent)
+        : parent(parent) {
+        size_t W = std::pow(2, parent.ngens);
+
+        for (size_t i = 0; i < W; ++i) {
+            results.emplace_back(W, std::nullopt);
+        }
+    }
+
+    tc::Cosets solve(const std::vector<int> &group_gens, const std::vector<int> &sub_gens) {
+        size_t group_key = key(group_gens);
+        size_t sub_key = key(sub_gens);
+
+        if (!results[group_key][sub_key]) {
+            results[group_key][sub_key] = parent.subgroup(group_gens).solve(sub_gens);
+        }
+
+        return results[group_key][sub_key].value();
+    }
+};