leetcode 24 -- Swap Nodes in Pairs
Swap Nodes in Pairs 题目： Given a linked list, swap every two adjacent nodes and return its head. For example, Given 1->2->3->4, y...
leetcode23 -- Merge k Sorted Lists
Merge k Sorted Lists 题目： Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes o...
leetcode 22 -- Generate Parentheses
Generate Parentheses 题目： Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. For example...
leetcode 21 -- Merge Two Sorted Lists
Merge Two Sorted Lists 题目： Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the node...
leetcode 20 -- Valid Parentheses
Valid Parentheses 题目： Given a string containing just the characters ‘(‘, ‘)’, ‘{‘, ‘}’, ‘[’ and ‘]’, determine if the input string is valid. ...
leetcode 19 -- Remove Nth Node From End of List
Remove Nth Node From End of List 题目： Given a linked list, remove the nth node from the end of list and return its head. For example, Give...
leetcode 18 -- 4Sum
4Sum 题目：Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the...
leetcode 17 -- Letter Combinations of a Phone Number
Letter Combinations of a Phone Number 题目： Given a digit string, return all possible letter combinations that the number could represent. A m...
leetcode 16 -- 3Sum Closest
3Sum Closest 题目： Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the su...
leetcode 15 -- 3Sum
3Sum 题目： Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which g...