leetcode

Given an m * n matrix M initialized with all 0's and several update operations. Operations are represented by a 2D array, and each operatio…

On a N * N grid, we place some 1 * 1 * 1 cubes. Each value v = grid[i][j] represents a tower of v cubes placed on top of grid cell (i, j). …

You have a list of points in the plane. Return the area of the largest triangle that can be formed by any 3 of the points. 根据题意，暴力破解，遍历各个点的…

Given a non-negative integer num, repeatedly add all its digits until the result has only one digit. 根据题意，把每位数字进行相加，最后一直加到得到一个十以内的数字即可，时间复杂…

leetcode 1009. Complement of Base 10 Integer ( Python ) 使用位运算解题

We then give 1 candy to the first person, 2 candies to the second person, and so on until we give n candies to the last person. Then, we go…

Given an array A of integers, for each integer A[i] we may choose any x with -K <= x <= K, and add x to A[i]. After this process, we have s…

Given a string S that only contains "I" (increase) or "D" (decrease), let N = S.length. 根据题意，找出规律，如果是 "I" 那就是找一个可选值的最小值，如果是 "D" 那就是找一个可选值的最…

On a N * N grid, we place some 1 * 1 * 1 cubes that are axis-aligned with the x, y, and z axes. Each value v = grid[i][j] represents a towe…

A self-dividing number is a number that is divisible by every digit it contains. For example, 128 is a self-dividing number because 128 % 1…

Given two strings s1, s2, find the lowest ASCII sum of deleted characters to make two strings equal. 根据题意，可以看出这种求最优的问题可以用 DP 算法来解决，其实直接使用 L…

A sequence of number is called arithmetic if it consists of at least three elements and if the difference between any two consecutive eleme…

In a country popular for train travel, you have planned some train travelling one year in advance. The days of the year that you will trave…

Given a string, your task is to count how many palindromic substrings in this string. The substrings with different start indexes or end in…

In a string S of lowercase letters, these letters form consecutive groups of the same character. For example, a string like S = "abbxxxxzyy…

Given a square array of integers A, we want the minimum sum of a falling path through A. A falling path starts at any element in the first …

Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. 根据题意，设置一个 sums 数组，长度为 len(nums)+1 ，索引…

Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary represent…

We are given a matrix with R rows and C columns has cells with integer coordinates (r, c), where 0 <= r < R and 0 <= c < C. Additionally, w…

Given two arrays, write a function to compute their intersection. 根据题意，先把两个列表排序，然后设置两个指针 i 和 j 遍历两个数组，判断是否有相同的元素，最后把结果都放入列表返回即可。时间复杂度为 O(Nl…