From 44e832e34ad7b1b39a06ec6b6b5404c9d01387d0 Mon Sep 17 00:00:00 2001
From: "codeflash-ai[bot]"
 <148906541+codeflash-ai[bot]@users.noreply.github.com>
Date: Sat, 21 Mar 2026 07:22:27 +0000
Subject: [PATCH] Optimize find_common_tags
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Reduced runtime from 11.3ms to 6.88ms (64% faster) by initializing the common set from the article with the fewest tags and avoiding the articles[1:] slice. Because set.intersection_update costs scale with the size of the left-hand set and slicing allocates a new list, starting from the smallest tag set cuts the amount of work and memory churn — the line profiler shows intersection_update’s share of time falling from ~54.8% to ~34.8% and the routine-level profile roughly halving. The trade-off is one extra O(n) scan to find the smallest tag list and a per-iteration skip check, which can regress on inputs consisting of many articles with uniformly tiny tag lists (observed ~15% slower in a couple large-uniform benchmarks), but it delivers clear wins for imbalanced or large tag collections.
---
 src/algorithms/string.py | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/src/algorithms/string.py b/src/algorithms/string.py
index 658439e..cf6e876 100644
--- a/src/algorithms/string.py
+++ b/src/algorithms/string.py
@@ -41,9 +41,27 @@ def find_common_tags(articles: list[dict[str, list[str]]]) -> set[str]:
     if not articles:
         return set()
 
-    common_tags = set(articles[0].get("tags", []))
-    for article in articles[1:]:
-        common_tags.intersection_update(article.get("tags", []))
+    # Find the article with the smallest tags list to initialize common_tags
+    min_idx = 0
+    min_len = len(articles[0].get("tags", []))
+    if min_len == 0:
+        return set()
+
+    for i in range(1, len(articles)):
+        tags_i = articles[i].get("tags", [])
+        li = len(tags_i)
+        if li < min_len:
+            min_len = li
+            min_idx = i
+            if min_len == 0:
+                return set()
+
+    common_tags = set(articles[min_idx].get("tags", []))
+    # Iterate over all articles except the one used to initialize common_tags
+    for i in range(len(articles)):
+        if i == min_idx:
+            continue
+        common_tags.intersection_update(articles[i].get("tags", []))
         if not common_tags:
             break
     return common_tags