Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. Example: Given a = 1 and b = 2, return 3. 转自https://discuss.leetcode.com/topic/49771/java-simple-easy-understand-solution-with-explanation/2,注意里面对于减法的讲解 h…
https://leetcode.com/problems/text-justification/ 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 approach; that is,…
Reverse bits of a given 32 bits unsigned integer. Example: Input: 43261596 Output: 964176192 Explanation: 43261596 represented in binary as 00000010100101000001111010011100, return 964176192 represented in binary as 00111001011110000010100101000000…
Given an integer, write an algorithm to convert it to hexadecimal. For negative integer, two’s complement method is used. Note: All letters in hexadecimal (a-f) must be in lowercase. The hexadecimal string must not contain extra leading 0s. If the nu…
这个题目思路就是比如101 的结果是010, 可以从111^101 来得到, 那么我们就需要知道刚好比101多一位的1000, 所以利用 while i <= num : i <<= 1, 去得到1000, 然后-1, 便得到111, 再跟num ^, 也就是异或即可. Code class Solution(object): def findComplement(self, num): i = 1 while i <= num: i <<= 1 return (i-1…
Given a non-empty array of numbers, a0, a1, a2, … , an-1, where 0 ≤ ai < 231. Find the maximum result of ai XOR aj, where 0 ≤ i, j < n. Could you do this in O(n) runtime? Example: Input: [3, 10, 5, 25, 2, 8] Output: 28 Explanation: The maximum resul…
Given N axis-aligned rectangles where N > 0, determine if they all together form an exact cover of a rectangular region. Each rectangle is represented as a bottom-left point and a top-right point. For example, a unit square is represented as [1,1,2,2…
Given two strings s and t which consist of only lowercase letters. String t is generated by random shuffling string s and then add one more letter at a random position. Find the letter that was added in t. Example: Input: s = "abcd" t = "ab…
Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. Example: Given a = 1 and b = 2, return 3. Credits:Special thanks to @fujiaozhu for adding this problem and creating all test cases. 这道题是CareerCup上的一道原题,难道…
Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate element must exist. Assume that there is only one duplicate number, find the duplicate one. Note: You must not modify t…
Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array. For example, Given nums = [0, 1, 3] return 2. Note: Your algorithm should run in linear runtime complexity. Could you implement it u…
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…
Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as the Hamming weight). For example, the 32-bit integer ’11' has binary representation 00000000000000000000000000001011, so the function should retu…
All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is sometimes useful to identify repeated sequences within the DNA. Write a function to find all the 10-letter-long seq…
Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times. You may assume that the array is non-empty and the majority element always exist in the array. Credits:Special thanks to @t…
Given an array of integers, every element appears three times except for one. Find that single one. Note:Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? 这道题是之前那道 Single Number 单独的数字的延伸,那道题的解法…
Divide two integers without using multiplication, division and mod operator. If it is overflow, return MAX_INT. 这道题让我们求两数相除,而且规定我们不能用乘法,除法和取余操作,那么我们还可以用另一神器位操作Bit Operation,思路是,如果被除数大于或等于除数,则进行如下循环,定义变量t等于除数,定义计数p,当t的两倍小于等于被除数时,进行如下循环,t扩大一倍,p扩大一倍,然后更…
原题链接在这里:https://leetcode.com/problems/power-of-four/ 题目: Given an integer (signed 32 bits), write a function to check whether it is a power of 4. Example:Given num = 16, return true. Given num = 5, return false. Follow up: Could you solve it without…
原题链接在这里:https://leetcode.com/problems/number-of-1-bits/ 题目: Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as the Hamming weight). For example, the 32-bit integer ’11' has binary representation 0…
原题链接在这里:https://leetcode.com/problems/generalized-abbreviation/ 题目: Write a function to generate the generalized abbreviations of a word. Example: Given word = "word", return the following list (order does not matter): ["word", "1…
Given a non-empty array of numbers, a0, a1, a2, - , an-1, where 0 ≤ ai < 231. Find the maximum result of ai XOR aj, where 0 ≤ i, j < n. Could you do this in O(n) runtime? Example: Input: [3, 10, 5, 25, 2, 8] Output: 28 Explanation: The maximum resul…
Given an integer, write a function to determine if it is a power of two. 分析:这道题让我们判断一个数是否为2的次方数(而且要求时间和空间复杂度都为常数),那么对于这种玩数字的题,我们应该首先考虑位操作 Bit Manipulation.在LeetCode中,位操作的题有很多,比如比如Repeated DNA Sequences 求重复的DNA序列, Single Number 单独的数字, Single Number…
题目 All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is sometimes useful to identify repeated sequences within the DNA. Write a function to find all the 10-letter-long…
