Range Sum Query 2D – Immutable Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by (row1, col1), (row2, col2). Example: Given matrix = [ [3, 0, 1, 4, 2], [5, 6, 3, 2, 1], [1, 2, 0, 1, 5], [4, 1, 0, 1, […]
Factor Combinations Numbers can be regarded as product of its factors. For example, 8 = 2 x 2 x 2; = 2 x 4. Write a function that takes an integer n and return all possible combinations of its factors. Note: Each combination’s factors must be sorted ascending, for example: […]
Given an array of numbers nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once. For example: Given nums = [1, 2, 1, 3, 2, 5], return [3, 5]. Note: The order of the result […]
Range Sum Query – Immutable Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. Example: Given nums = [-2, 0, 3, -5, 2, -1] sumRange(0, 2) -> 1 sumRange(2, 5) -> -1 sumRange(0, 5) -> -3 Note: You may […]
Smallest Rectangle Enclosing Black Pixels An image is represented by a binary matrix with 0 as a white pixel and 1 as a black pixel. The black pixels are connected, i.e., there is only one black region. Pixels are connected horizontally and vertically. Given the location (x, y) of one […]
第一天 水卢 多伦多 Lga起飞 westjet航班 还好提前买了可以carry on的行李箱 换了登机牌 但因为水杯里的水没倒干净 又得出去重新过一遍安检 机场有30min的免费wifi 超过的部分只好连接手机的wifi热点。 纽约到多伦多的航行比我想象中的要短 一个半小时便到了。Yyz机场附近的房子很矮，零星地散落。 aiabnb的房间 在 basement 房主叫erica 挺nice的。当我说，我周围哪里有卖早点的店铺时，她说，你直接吃我的面包吧，没问题的。感动。 感谢上帝 一开始在avis租车，预定过了，也电话确认过，但到现场却不给我租，说是因为我没有在加拿大的开车经验，差点跟他吵起来。店铺和网上讲的完全不同。 还好，又走了走，找到了hertz。我直接主动跟他讲我的驾照，护照，但没提驾驶经验。然后就租给我了。买了LDW，虽然很贵，但是放心。 一路无事，抵达多伦多。期间朋友的护照忘带了，我们定的是青旅，怕不让checkin。我说没事，我来安排。还好前台的人员说只要一个护照就好。有惊无险，要不然得开回多伦多了。 捷达 叔叔的最爱，话说好几个月没开车了，刚提到车时心还是虚的。磨磨蹭蹭地在停车场里练习前进后退，再在路上小心地绕了两圈，才开到女友家楼下。一路上一直担心，还好最终平安无事。虽然最后从Niagara Fall开回水卢时整个人都虚脱了。 第二天逛了多伦多市内，第三天去大瀑布。第四天回纽约。 四天的旅程下来，深刻体会到，只有两情相悦才能走的长久。自己之前妄图用真心感动对方，其实还是太幼稚了。
Remove Invalid Parentheses Remove the minimum number of invalid parentheses in order to make the input string valid. Return all possible results. Note: The input string may contain letters other than the parentheses ( and ). Examples: “()())()” -> [“()()()”, “(())()”] “(a)())()” -> [“(a)()()”, “(a())()”] “)(” -> [“”] Credits: Special […]
Longest Increasing Subsequence Given an unsorted array of integers, find the length of longest increasing subsequence. For example, Given [10, 9, 2, 5, 3, 7, 101, 18], The longest increasing subsequence is [2, 3, 7, 101], therefore the length is 4. Note that there may be more than one LIS […]
Integer to English Words Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 – 1. For example, 123 -> “One Hundred Twenty Three” 12345 -> “Twelve Thousand Three Hundred Forty Five” 1234567 -> “One Million Two Hundred Thirty Four Thousand Five […]
Bulls and Cows You are playing the following Bulls and Cows game with your friend: You write a 4-digit secret number and ask your friend to guess it, each time your friend guesses a number, you give a hint, the hint tells your friend how many digits are in the […]