From 3ba6cad899ec4106b84e5296b1c715c244ad511c Mon Sep 17 00:00:00 2001
From: Denis Kazakov <86667459+Denis-Kazakov@users.noreply.github.com>
Date: Sat, 6 Sep 2025 12:54:08 +0300
Subject: [PATCH] Update 11_selection.md

Fix bug. Code on page 127 in pdf failed with this trace:
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[19], line 1
----> 1 secondsmallest(L)

Cell In[18], line 5, in secondsmallest(L)
      3 a, b = None, None
      4 for item in L:
----> 5     if a is None or item <= b:
      6         a, b = item, a
      7     elif b is None or item <= a:

TypeError: '<=' not supported between instances of 'int' and 'NoneType'
---
 prose/11_selection.md | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/prose/11_selection.md b/prose/11_selection.md
index 88a69e8..4ec0816 100644
--- a/prose/11_selection.md
+++ b/prose/11_selection.md
@@ -24,12 +24,16 @@ If our goal is to find the second largest item in a list, we could do this in li
 
 ```python
 def secondsmallest(L):
-    a, b = None, None
-    for item in L:
-        if a is None or item <= b:
-            a, b = item, a
-        elif b is None or item <= a:
-            b = item
+    if len(L) < 2:
+        return None
+    a, b = L[0], L[1]
+    if a > b:
+        a, b = b, a
+    for i in range(2, len(L)):
+        if L[i] <= a:
+            a, b = L[i], a
+        elif L[i] < b:
+            b = L[i]
     return b
 ```