fix: Use hashmap for quicker lookup in assembleAdd

src/libxrpl/protocol/STPathSet.cpp

@@ -51,6 +51,12 @@ STPathElement::getHash(STPathElement const& element)
     return (hashAccount ^ hashCurrency ^ hashIssuer);
 }
 
+[[nodiscard]] size_t
+STPathElement::getHash() const
+{
+    return STPathElement::getHash(*this);
+}
+
 STPathSet::STPathSet(SerialIter& sit, SField const& name) : STBase(name)
 {
     std::vector<STPathElement> path;
@@ -126,21 +132,15 @@ STPathSet::move(std::size_t n, void* buf)
 bool
 STPathSet::assembleAdd(STPath const& base, STPathElement const& tail)
 {  // assemble base+tail and add it to the set if it's not a duplicate
-    value_.push_back(base);
+    STPath combined = base;
+    combined.pushBack(tail);
 
-    auto it = value_.rbegin();
-
-    STPath& newPath = *it;
-    newPath.pushBack(tail);
-
-    while (++it != value_.rend())
+    if (!seenHashes_.insert(combined).second)
     {
-        if (*it == newPath)
-        {
-            value_.pop_back();
-            return false;
-        }
+        return false;
     }
+
+    value_.push_back(std::move(combined));
     return true;
 }