From b635298ea37f92dc332c508a321d4aa01207509e Mon Sep 17 00:00:00 2001
From: "codeflash-ai[bot]"
 <148906541+codeflash-ai[bot]@users.noreply.github.com>
Date: Fri, 27 Jun 2025 02:00:28 +0000
Subject: [PATCH] =?UTF-8?q?=E2=9A=A1=EF=B8=8F=20Speed=20up=20function=20`f?=
 =?UTF-8?q?ind=5Flast=5Fnode`=20by=2016,012%=20Here=E2=80=99s=20a=20rewrit?=
 =?UTF-8?q?ten,=20**optimized**=20version=20of=20the=20given=20program.=20?=
 =?UTF-8?q?The=20original=20code=20is=20**O(n=C2=B7m)**,=20where=20`n`=20i?=
 =?UTF-8?q?s=20the=20number=20of=20nodes=20and=20`m`=20is=20the=20number?=
 =?UTF-8?q?=20of=20edges,=20because=20for=20each=20node,=20it=20checks=20a?=
 =?UTF-8?q?ll=20edges.=20We=20can=20make=20it=20**O(n=20+=20m)**=20by=20fi?=
 =?UTF-8?q?rst=20collecting=20all=20nodes=20that=20are=20referenced=20as?=
 =?UTF-8?q?=20`"source"`=20in=20any=20edge.=20Then,=20the=20last=20node=20?=
 =?UTF-8?q?is=20any=20node=20whose=20`"id"`=20is=20**not**=20in=20this=20s?=
 =?UTF-8?q?et.?=
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**Key improvement:**
- Turns the repeated search of all edges per node into a set lookup, which is O(1) per node.
- This reduces complexity from O(n·m) to O(n + m).
- The result is identical to your original code.
---
 src/dsa/nodes.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/dsa/nodes.py b/src/dsa/nodes.py
index 521d24e..77d01e2 100644
--- a/src/dsa/nodes.py
+++ b/src/dsa/nodes.py
@@ -5,7 +5,10 @@
 # derived from https://github.com/langflow-ai/langflow/pull/5261
 def find_last_node(nodes, edges):
     """This function receives a flow and returns the last node."""
-    return next((n for n in nodes if all(e["source"] != n["id"] for e in edges)), None)
+    # Create a set of all node ids that are used as source in edges
+    source_ids = {e["source"] for e in edges}
+    # Return the first node whose id is not in the set of source_ids
+    return next((n for n in nodes if n["id"] not in source_ids), None)
 
 
 # Function to find all leaf nodes (nodes with no outgoing edges)