6 days

leetcode/longest_palindromic_substring.py

@@ -16,12 +16,12 @@
 
 '''
 
-# Brute force approach - O(n) time, O(n) space
+# Brute force approach - O(n^3) time, O(1) space
 def longestPalindrome(self, s):
 	longest_str = ''
 	for i in range(len(s)):
 		for j in range(i, len(s) + 1):
-			temp = s[s:j]
-			if temp == temp[::-1] and len(temp) > len(longest_str):
+			temp = s[i:j]
+			if temp == temp[::-1] and len(temp) >= len(longest_str):
 				longest_str = temp
-				print(temp)
+	return longest_str

leetcode/single_number.py

@@ -0,0 +1,32 @@
+
+'''
+136. Single Number
+
+Given a non-empty array of integers, every element appears twice except for one. Find that single one.
+
+Note:
+
+Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
+
+Example 1:
+Input: [2,2,1]
+Output: 1
+
+Example 2:
+Input: [4,1,2,1,2]
+Output: 4
+
+'''
+
+# Dictionary approach - O(n) time, O(n) space
+def singleNumber(self, nums):
+	d = {}
+	for item in nums:
+		if item in d:
+			d[item] += 1
+		else: 
+			d[item] = 1
+
+	for key, value in d.items():
+		if value == 1:
+			return key