Generate Parentheses
Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. For example, given n = 3, a solution set is: "((()))", "(()())", "(())()", "()(())", "()()()"...
View ArticleContainer With Most Water
Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Find two...
View ArticleMerge Two Sorted Lists
Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. 题目的意思是给定两个有序的链表，将它们合并为一个有序的链表。...
View ArticleRemove Nth Node From End of List
Given a linked list, remove the nth node from the end of list and return its head. For example, Given linked list: 1->2->3->4->5, and n = 2. After removing the second node from the end,...
View ArticleValid Parentheses
Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. The brackets must close in the correct order, "()" and "()[]{}" are all valid but...
View ArticleImplement strStr()
Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack....
View ArticleRemove Duplicates from Sorted Array
Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length. Do not allocate extra space for another array, you must do this in place with...
View ArticleRemove Element
Given an array and a value, remove all instances of that value in place and return the new length. The order of elements can be changed. It doesn't matter what you leave beyond the new length....
View ArticleDivide Two Integers
Divide two integers without using multiplication, division and mod operator. If it is overflow, return MAX_INT. 题目要求我们不用乘法，除法还有模运算来完成两个整数的除运算。如果溢出时返回最大值。...
View ArticleNext Permutation 全排列
mplement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers. If such arrangement is not possible, it must rearrange it as the lowest possible...
View ArticleSearch in Rotated Sorted Array
Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). You are given a target value to search. If found in the array return its...
View ArticleSearch for a Range
Given a sorted array of integers, find the starting and ending position of a given target value. Your algorithm's runtime complexity must be in the order of O(log n). If the target is not found in the...
View ArticleSearch Insert Position
Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order. You may assume no duplicates in the array....
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Valid Sudoku 数独
Determine if a Sudoku is valid. The Sudoku board could be partially filled, where empty cells are filled with the character '.'. A partially filled sudoku which is valid. Note: A valid Sudoku board...
View ArticleCount and Say
The count-and-say sequence is the sequence of integers beginning as follows: 1, 11, 21, 1211, 111221, ... 1 is read off as "one 1" or 11. 11 is read off as "two 1s" or 21. 21 is read off as "one 2,...
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