From 80d4626ada33c7f717610871dea28f859c3aaf6d Mon Sep 17 00:00:00 2001
From: Cameron Yick <cameron.yick@yale.edu>
Date: Mon, 26 Dec 2016 13:15:54 -0500
Subject: [PATCH 1/2] Optimize all-unique-characters.py
Was thinking about this problem recently, so added a small constraint that avoids checking strings that must have duplicates by virtue of the fact that they are too long.
Alternately, if it would be best to code up a separate solution in a different file, I could do that too.
---
solutions/python/all-unique-characters.py | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/solutions/python/all-unique-characters.py b/solutions/python/all-unique-characters.py
index 9224d9b..5e14bf4 100644
--- a/solutions/python/all-unique-characters.py
+++ b/solutions/python/all-unique-characters.py
@@ -3,8 +3,14 @@
import unittest
def all_unique(string):
+
+ # Optimization that assumes only 255 ASCII characters are possible (ignores possibility of unicode)
+ nLetters = len(letters)
+ if (nLetters > 255):
+ return False
+
letters = sorted(string)
- for i in range(len(letters) - 1):
+ for i in range(nLetters - 1):
if letters[i] == letters[i + 1]:
return False
return True
From 58e6d425da4b160d1b7efb5082a9379bbdfd589c Mon Sep 17 00:00:00 2001
From: Cameron Yick <cameron.yick@yale.edu>
Date: Thu, 9 Feb 2017 19:52:59 -0500
Subject: [PATCH 2/2] Set correct number of ASCII characters
There are 256, not 255 characters
The classic CS off-by-one error strikes again
---
solutions/python/all-unique-characters.py | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/solutions/python/all-unique-characters.py b/solutions/python/all-unique-characters.py
index 5e14bf4..b7b96fc 100644
--- a/solutions/python/all-unique-characters.py
+++ b/solutions/python/all-unique-characters.py
@@ -4,9 +4,9 @@
def all_unique(string):
- # Optimization that assumes only 255 ASCII characters are possible (ignores possibility of unicode)
+ # Optimization that assumes only 256 (2^8) ASCII characters are possible (ignores possibility of unicode)
nLetters = len(letters)
- if (nLetters > 255):
+ if (nLetters > 256):
return False
letters = sorted(string)