op_yu的专栏

题目：Follow up for "Remove Duplicates":What if duplicates are allowed at most twice?For example,Given sorted array A = [1,1,1,2,2,3],Your function should return length = 5, and A is no

题目：Given a collection of intervals, merge all overlapping intervals.For example,Given [1,3],[2,6],[8,10],[15,18],return [1,6],[8,10],[15,18].解法：timu

题目：The set [1,2,3,…,n] contains a total of n! unique permutations.By listing and labeling all of the permutations in order,We get the following sequence (ie, for n = 3):"123""132""21

题目：The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.Given an integer n, return all distinct solutions to the n-queens

题目：Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.If the last word does not exist, return 0.Note: 

题目：Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.For example,Given n = 3,You should return the following matrix:[ [ 1, 2, 3 ], [ 8, 9

题目：A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).The robot can only move either down or right at any point in time. The robot is trying to r

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 of the first two lists.解法：实际上就是归并排序的lian

题目：Given two binary strings, return their sum (also a binary string).For example,a = "11"b = "1"Return "100".解法：

题目：Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximum jump length at that position.De

题目：Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.For example,Given the following matrix:[ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9

题目：Given an array of strings, return all groups of strings that are anagrams.Note: All inputs will be in lower-case.解法：所谓的anagrams是指

题目：You are given an n x n 2D matrix representing an image.Rotate the image by 90 degrees (clockwise).Follow up:Could you do this in-place?解法：shunshiji

题目：Implement pow(x, n).解法：题目要求shi

题目：Given a collection of numbers that might contain duplicates, return all possible unique permutations.For example,[1,1,2] have the following unique permutations:[1,1,2], [1,2,1], and

题目：Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining.For example, Given [0,1,0,2,1,0,1,3

题目：Given a collection of numbers, return all possible permutations.For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].解法：要

题目：Follow up for N-Queens problem.Now, instead outputting board configurations, return the total number of distinct solutions.解法：jiefa

题目：Find the contiguous subarray within an array (containing at least one number) which has the largest sum.For example, given the array [−2,1,−3,4,−1,2,1,−5,4],the contiguous subarra

题目：Given a non-negative number represented as an array of digits, plus one to the number.The digits are stored such that the most significant digit is at the head of the list.解法：

题目：Given a list, rotate the list to the right by k places, where k is non-negative.For example:Given 1->2->3->4->5->NULL and k = 2,return 4->5->1->2->3->NULL.解法：

题目：Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).You may assume that the intervals were initially sorted according to their start ti

题目：Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).For example,S = "ADOBECODEBANC"T = "ABC"Minimum windo

题目：Follow up for "Search in Rotated Sorted Array":What if duplicates are allowed?Would this affect the run-time complexity? How and why?Write a function to determine if a given target

题目：Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.For example,Given 1->2->3->3->4->4->5, return 1->2->5.Gi

题目:Given an array of words and a length L, format the text such that each line has exactly L characters and is fully (left and right) justified.You should pack your words in a greedy approac

题目：Given an absolute path for a file (Unix-style), simplify it.For example,path = "/home/", => "/home"path = "/a/./b/../../c/", => "/c"click to show corner cases.Corner Cases:

题目：Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:Integers in each row are sorted from left to right.The first intege

题目：Given a set of distinct integers, S, return all possible subsets.Note:Elements in a subset must be in non-descending order.The solution set must not contain duplicate subsets.

题目：Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.click to show follow up.Follow up:Did you use extra space?A straight forward solution

题目：Given a sorted linked list, delete all duplicates such that each element appear only once.For example,Given 1->1->2, return 1->2.Given 1->1->2->3->3, return 1->2->3.解法：Remove Dupl

题目：Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path.解法：

题目:Follow up for "Unique Paths":Now consider if some obstacles are added to the grids. How many unique paths would there be?An obstacle and empty space is marked as 1 and 0 respectively

题目：Validate if a given string is numeric.Some examples:"0" => true" 0.1 " => true"abc" => false"1 a" => false"2e10" => trueNote: It is intended for the problem statement to b

题目：mplement int sqrt(int x).Compute and return the square root of x.解法：和前面的不用che

题目：You are climbing a stair case. It takes n steps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?解法：采用DP算法，找到递推关系式。

题目：Given two words word1 and word2, find the minimum number of steps required to convert word1 to word2. (each operation is counted as 1 step.)You have the following 3 operations permitted o

题目：Given an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, white and blue.Here, we will use the

题目：Given two integers n and k, return all possible combinations of k numbers out of 1 ... n.For example,If n = 4 and k = 2, a solution is:[ [2,4], [3,4], [2,3], [1,2], [1,3],

题目：Implement regular expression matching with support for '.' and '*'.'.' Matches any single character.'*' Matches zero or more of the preceding element.The matching should cover the entire