Solutions to All Leetcode Problems with Python

I finally finished all the 154 Leetcode problems in Python. 
In my blog, I try to post the most succinct and effective Python solutions to Leetcode problems. You are more than welcome to post your solutions in the comments if you think yours are better. 
I will add on explanations to the solutions later. 
I also want to thank the following two bloggers. 水中的鱼 explains the algorithms in a clear and succinct way. Kitt's blog is the best Python leetcode solution blog so far.

Title	Algorith&Data Structure	AC Rates
Single Number		45.90%
Maximum Depth of Binary Tree		43.90%
Same Tree		42.20%
Reverse Integer		40.20%
Best Time to Buy and Sell Stock II		36.80%
Unique Binary Search Trees		36.40%
Linked List Cycle		35.90%
Binary Tree Preorder Traversal		35.60%
Binary Tree Inorder Traversal		35.60%
Populating Next Right Pointers in Each Node		35.30%
Search Insert Position		35.00%
Remove Duplicates from Sorted List		35.00%
Climbing Stairs	DP	34.00%
Roman to Integer		33.90%
Single Number II		33.80%
Maximum Subarray		33.80%
Integer to Roman		33.70%
Remove Element		33.40%
Merge Two Sorted Lists		33.30%
N-Queens II	BFS, iterator	33.20%
Balanced Binary Tree		32.70%
Convert Sorted Array to Binary Search Tree		32.60%
Remove Duplicates from Sorted Array		32.40%
Swap Nodes in Pairs		32.40%
Symmetric Tree		32.20%
Sort Colors		32.10%
Merge Sorted Array		32.10%
Gray Code		32.00%
Pascal's Triangle		31.70%
Find Minimum in Rotated Sorted Array	log(n)	31.60%
Plus One		31.60%
Generate Parentheses		31.50%
Rotate Image		31.50%
Unique Paths		31.50%
Container With Most Water		31.30%
Binary Tree Level Order Traversal II		31.30%
Permutations		31.30%
Minimum Path Sum		31.20%
Search a 2D Matrix		31.10%
Best Time to Buy and Sell Stock		31.00%
Set Matrix Zeroes		30.90%
Linked List Cycle II		30.90%
Binary Tree Postorder Traversal		30.90%
Spiral Matrix II		30.80%
Binary Tree Level Order Traversal		30.80%
Search in Rotated Sorted Array II		30.70%
Remove Duplicates from Sorted Array II		30.60%
Path Sum		30.60%
Pascal's Triangle II		30.50%
Populating Next Right Pointers in Each Node II		30.40%
Combinations		30.40%
Remove Nth Node From End of List		29.90%
Sum Root to Leaf Numbers		29.80%
Minimum Depth of Binary Tree		29.60%
Length of Last Word		29.50%
Palindrome Number		29.00%
Trapping Rain Water		28.70%
Search in Rotated Sorted Array		28.60%
Valid Parentheses		28.40%
Longest Consecutive Sequence		28.10%
Flatten Binary Tree to Linked List		28.10%
Subsets		27.90%
Valid Sudoku		27.90%
Unique Paths II		27.80%
Search for a Range		27.50%
Count and Say		27.30%
Unique Binary Search Trees II		27.30%
Convert Sorted List to Binary Search Tree		27.30%
Longest Common Prefix		27.20%
Jump Game		27.20%
3Sum Closest		27.10%
Subsets II		27.00%
Path Sum II		27.00%
Partition List		26.80%
Triangle		26.70%
Binary Tree Zigzag Level Order Traversal		26.70%
Combination Sum		26.60%
Construct Binary Tree from Preorder and Inorder Traversal		26.50%
Construct Binary Tree from Inorder and Postorder Traversal		26.40%
Letter Combinations of a Phone Number		26.30%
Reverse Linked List II		26.00%
N-Queens	BFS/iterator	26.00%
Add Binary		26.00%
Pow(x, n)		25.90%
Palindrome Partitioning		25.90%
Validate Binary Search Tree		25.90%
Find Minimum in Rotated Sorted Array II	log(n)	25.80%
Gas Station		25.70%
Next Permutation		25.40%
Edit Distance		25.30%
Insertion Sort List		25.30%
Permutations II		25.10%
Remove Duplicates from Sorted List II		24.90%
Reverse Nodes in k-Group		24.90%
Distinct Subsequences		24.80%
Jump Game II		24.70%
Combination Sum II		24.60%
ZigZag Conversion		23.90%
Anagrams		23.60%
Recover Binary Search Tree		23.50%
Copy List with Random Pointer		23.20%
Add Two Numbers		23.10%
Valid Palindrome		22.90%
Clone Graph		22.80%
Scramble String		22.60%
First Missing Positive		22.50%
Sqrt(x)		22.30%
Longest Substring Without Repeating Characters		22.30%
Best Time to Buy and Sell Stock III		22.20%
Rotate List		22.10%
Permutation Sequence		22.10%
Merge k Sorted Lists		21.90%
Implement strStr()		21.80%
4Sum		21.60%
Maximal Rectangle		21.60%
Largest Rectangle in Histogram		21.20%
Word Break		21.10%
Sudoku Solver		20.80%
Merge Intervals		20.80%
Longest Palindromic Substring		20.80%
Spiral Matrix		20.60%
Insert Interval		20.60%
Sort List		20.50%
Multiply Strings		20.50%
Restore IP Addresses		20.50%
Reorder List		20.30%
Binary Tree Maximum Path Sum		20.00%
Regular Expression Matching		19.90%
Evaluate Reverse Polish Notation		19.90%
Word Search		19.90%
Simplify Path		19.90%
Longest Valid Parentheses		19.60%
Interleaving String		19.20%
Candy		19.00%
Two Sum		18.50%
Word Ladder		18.30%
Palindrome Partitioning II		18.00%
Minimum Window Substring		18.00%
Substring with Concatenation of All Words		18.00%
Median of Two Sorted Arrays		17.40%
3Sum		16.90%
Word Break II		16.40%
Divide Two Integers		16.30%
Maximum Product Subarray	DP/list	16.20%
Min Stack		16.20%
Decode Ways		16.10%
String to Integer (atoi)		14.70%
Surrounded Regions		14.20%
Reverse Words in a String		14.10%
LRU Cache		14.00%
Text Justification		14.00%
Wildcard Matching		13.80%
Word Ladder II		11.30%
Valid Number		11.00%
Max Points on a Line		10.90%