leetcode中等题

#	Title	Solution	Acceptance	Difficulty	Frequency
	1	Two Sum		44.5%	Easy
	2	Add Two Numbers		31.7%	Medium
	3	Longest Substring Without Repeating Characters		28.8%	Medium
	4	Median of Two Sorted Arrays		27.2%	Hard
	5	Longest Palindromic Substring		27.8%	Medium
	10	Regular Expression Matching		25.6%	Hard
	11	Container With Most Water		46.3%	Medium
	15	3Sum		24.7%	Medium
	17	Letter Combinations of a Phone Number		42.8%	Medium
	19	Remove Nth Node From End of List		34.5%	Medium
	20	Valid Parentheses		37.1%	Easy
	21	Merge Two Sorted Lists		48.6%	Easy
	22	Generate Parentheses		56.7%	Medium
	23	Merge k Sorted Lists		35.8%	Hard
	31	Next Permutation		31.0%	Medium
	32	Longest Valid Parentheses		26.2%	Hard
	33	Search in Rotated Sorted Array		33.1%	Medium
	34	Find First and Last Position of Element in Sorted Array		34.1%	Medium
	39	Combination Sum		50.4%	Medium
	42	Trapping Rain Water		44.4%	Hard
	46	Permutations		57.1%	Medium
	48	Rotate Image		50.3%	Medium
	49	Group Anagrams		48.9%	Medium
	53	Maximum Subarray		44.4%	Easy
	55	Jump Game		32.5%	Medium
	56	Merge Intervals		36.5%	Medium
	62	Unique Paths		48.9%	Medium
	64	Minimum Path Sum		48.3%	Medium
	70	Climbing Stairs		44.9%	Easy
	72	Edit Distance		39.1%	Hard
	75	Sort Colors		43.1%	Medium
	76	Minimum Window Substring		31.7%	Hard
	78	Subsets		54.7%	Medium
	79	Word Search		32.2%	Medium
	84	Largest Rectangle in Histogram		32.1%	Hard
	85	Maximal Rectangle		34.4%	Hard
	94	Binary Tree Inorder Traversal		58.2%	Medium
	96	Unique Binary Search Trees		47.5%	Medium
	98	Validate Binary Search Tree		26.2%	Medium
	101	Symmetric Tree		44.2%	Easy
	102	Binary Tree Level Order Traversal		49.9%	Medium
	104	Maximum Depth of Binary Tree		61.8%	Easy
	105	Construct Binary Tree from Preorder and Inorder Traversal		42.8%	Medium
	114	Flatten Binary Tree to Linked List		43.8%	Medium
	121	Best Time to Buy and Sell Stock		48.1%	Easy
	124	Binary Tree Maximum Path Sum		30.8%	Hard
	128	Longest Consecutive Sequence		42.5%	Hard
	136	Single Number		61.3%	Easy
	139	Word Break		36.4%	Medium
	141	Linked List Cycle		37.9%	Easy
	142	Linked List Cycle II		33.3%	Medium
	146	LRU Cache		27.0%	Medium
	148	Sort List		36.9%	Medium
	152	Maximum Product Subarray		29.9%	Medium
	155	Min Stack		38.5%	Easy
	160	Intersection of Two Linked Lists		35.3%	Easy
	169	Majority Element		53.9%	Easy
	198	House Robber		41.3%	Easy
	200	Number of Islands		42.6%	Medium
	206	Reverse Linked List		56.5%	Easy
	207	Course Schedule		39.0%	Medium
	208	Implement Trie (Prefix Tree)		40.2%	Medium
	215	Kth Largest Element in an Array		49.5%	Medium
	221	Maximal Square		33.9%	Medium
	226	Invert Binary Tree		59.4%	Easy
	234	Palindrome Linked List		36.9%	Easy
	236	Lowest Common Ancestor of a Binary Tree		39.2%	Medium
	238	Product of Array Except Self		56.3%	Medium
	239	Sliding Window Maximum		39.1%	Hard
	240	Search a 2D Matrix II		41.3%	Medium
	253	Meeting Rooms II		43.4%	Medium
	279	Perfect Squares		42.9%	Medium
	283	Move Zeroes		55.0%	Easy
	287	Find the Duplicate Number		50.8%	Medium
	295	Find Median from Data Stream		38.2%	Hard
	297	Serialize and Deserialize Binary Tree		42.3%	Hard
	300	Longest Increasing Subsequence		41.3%	Medium
	301	Remove Invalid Parentheses		40.1%	Hard
	309	Best Time to Buy and Sell Stock with Cooldown		44.7%	Medium
	312	Burst Balloons		48.3%	Hard
	322	Coin Change		31.6%	Medium
	337	House Robber III		48.7%	Medium
	338	Counting Bits		65.5%	Medium
	347	Top K Frequent Elements		56.3%	Medium
	394	Decode String		46.1%	Medium
	399	Evaluate Division		48.5%	Medium
	406	Queue Reconstruction by Height		60.8%	Medium
	416	Partition Equal Subset Sum		41.5%	Medium
	437	Path Sum III		43.5%	Easy
	438	Find All Anagrams in a String		38.2%	Medium
	448	Find All Numbers Disappeared in an Array		54.1%	Easy
	494	Target Sum		45.7%	Medium
	538	Convert BST to Greater Tree		52.1%	Easy
	543	Diameter of Binary Tree		47.3%	Easy
	560	Subarray Sum Equals K		42.8%	Medium
	581	Shortest Unsorted Continuous Subarray		30.4%	Easy
	617	Merge Two Binary Trees		71.0%	Easy
	621	Task Scheduler		46.2%	Medium
	647	Palindromic Substrings		57.7%	Medium
	739	Daily Temperatures		60.5%	Medium