Spiral Matrix 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 ] ] You should return [1,2,3,6,9,8,7,4,5]. 思路:螺旋数…

之前切了道求解最大正方形的题,题解猛戳 这里.这道题 Maximal Rectangle 题意与之类似,但是解法完全不一样. 先来看这道题 Largest Rectangle in Histogram,如果暴力求解,可以枚举每个点为最小值,向两边扩展,复杂度 O(n^2).我们可以维护一个栈,从而将复杂度降低到 O(n),这个栈的思维非常巧妙,参考了 discuss,我是完全想不出来(或者说忘记了).具体代码可以猛戳 这里. 2016-08-07 补:stack 数组维护的是一个单调递增的数组,…

Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area. 思路:此题的意思是给一个为0或1的矩阵,求所有为1组成的最大矩阵的面积. 此题能够巧妙转化为求最大直方图面积的问题. public class Solution { //其思想是将每一列的1逐行相加,遇0为0.遇1相加 //然后转化为求每一行的最大直方图面积的求解…

链接: https://leetcode.com/problems/maximal-rectangle/ [描述] Given a 2D binary matrix filled with '0's and '1's, find the largest rectangle containing all ones and return its area. [中文描述] 给一个二维数组, 算出里面最大的全1矩形面积,比如: [ ['1','1','1','0'], ['1','1','1','1']…

Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing only 1's and return its area. Example: Input: [ ["1","0","1","0","0"], ["1","0","1",&qu…

给定一个只含0和1的数组,求含1的最大矩形面积. Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area. 这样的题一般看来都是有O(n*m)的解法的. 借助上一题Largest Rectangle in Histogram 的解法. 我们现在把矩阵的每一行当做是上一题的问题,然后遍历所有的行数,取最大数就是解. 这里的…

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 integer of each row is greater than the last integer of the previous ro…

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 integers 0, 1, and 2 to represent the color red, white, and bl…

Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x. You should preserve the original relative order of the nodes in each of the two partitions. For example, Given 1->4->3->…

3Sum  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 gives the sum of zero. Note: Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c) The…