From 93a954dd33c8c9abd943c6a7a9fbead27259af3f Mon Sep 17 00:00:00 2001
From: dbanks12 <david@aztecprotocol.com>
Date: Thu, 30 Mar 2023 14:27:49 +0000
Subject: [PATCH 1/2] compute merkle tree

---
 .../barretenberg/stdlib/merkle_tree/hash.hpp  | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/cpp/src/barretenberg/stdlib/merkle_tree/hash.hpp b/cpp/src/barretenberg/stdlib/merkle_tree/hash.hpp
index 27da44cf5a..f763f1fa45 100644
--- a/cpp/src/barretenberg/stdlib/merkle_tree/hash.hpp
+++ b/cpp/src/barretenberg/stdlib/merkle_tree/hash.hpp
@@ -58,6 +58,29 @@ inline barretenberg::fr compute_tree_root_native(std::vector<barretenberg::fr> c
     return layer[0];
 }
 
+inline std::vector<barretenberg::fr> compute_tree_native(std::vector<barretenberg::fr> const& input)
+{
+    // Check if the input vector size is a power of 2.
+    ASSERT(input.size() > 0);
+    ASSERT(numeric::is_power_of_two(input.size()));
+    auto layer = input;
+    std::vector<barretenberg::fr> tree(input);
+    while (layer.size() > 1) {
+        std::vector<barretenberg::fr> next_layer(layer.size() / 2);
+        for (size_t i = 0; i < next_layer.size(); ++i) {
+            if (plonk::SYSTEM_COMPOSER == plonk::PLOOKUP) {
+                next_layer[i] = crypto::pedersen_hash::lookup::hash_multiple({ layer[i * 2], layer[i * 2 + 1] });
+            } else {
+                next_layer[i] = crypto::pedersen_hash::hash_multiple({ layer[i * 2], layer[i * 2 + 1] });
+            }
+            tree.push_back(next_layer[i]);
+        }
+        layer = std::move(next_layer);
+    }
+
+    return tree;
+}
+
 } // namespace merkle_tree
 } // namespace stdlib
 } // namespace plonk

From 730fd46796a312ca18cb2094a000a11ee043d891 Mon Sep 17 00:00:00 2001
From: dbanks12 <david@aztecprotocol.com>
Date: Thu, 30 Mar 2023 14:32:08 +0000
Subject: [PATCH 2/2] compute tree comment

---
 cpp/src/barretenberg/stdlib/merkle_tree/hash.hpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/cpp/src/barretenberg/stdlib/merkle_tree/hash.hpp b/cpp/src/barretenberg/stdlib/merkle_tree/hash.hpp
index f763f1fa45..a99b2d6435 100644
--- a/cpp/src/barretenberg/stdlib/merkle_tree/hash.hpp
+++ b/cpp/src/barretenberg/stdlib/merkle_tree/hash.hpp
@@ -58,6 +58,7 @@ inline barretenberg::fr compute_tree_root_native(std::vector<barretenberg::fr> c
     return layer[0];
 }
 
+// TODO write test
 inline std::vector<barretenberg::fr> compute_tree_native(std::vector<barretenberg::fr> const& input)
 {
     // Check if the input vector size is a power of 2.