Given a chemical formula (given as a string), return the count of each atom. An atomic element always starts with an uppercase character, then zero or more lowercase letters, representing the name. 1 or more digits representing the count of that elem…

原题链接在这里:https://leetcode.com/problems/number-of-atoms/description/ 题目: Given a chemical formula (given as a string), return the count of each atom. An atomic element always starts with an uppercase character, then zero or more lowercase letters, repr…

leetcode:Number of 1 Bits 代码均测试通过! 1.Number of 1 Bits 本题收获: 1.Hamming weight:即二进制中1的个数 2.n &= (n-1)[n = n & (n-1)]的用处 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).…

原题链接在这里:https://leetcode.com/problems/number-of-digit-one/ 每10个数, 有一个个位是1, 每100个数, 有10个十位是1, 每1000个数, 有100个百位是1.  做一个循环, 每次计算单个位上1得总个数(个位,十位, 百位). 例子: 以算百位上1为例子:   假设百位上是0, 1, 和 >=2 三种情况: case 1: n=3141092, a= 31410, b=92. 计算百位上1的个数应该为 3141 *100 次. c…

LeetCode--Number Complement Question Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation. Note: The given integer is guaranteed to fit within the range of a 32-bit signed in…

LeetCode--Number of Boomerangs Question Given n points in the plane that are all pairwise distinct, a "boomerang" is a tuple of points (i, j, k) such that the distance between i and j equals the distance between i and k (the order of the tuple m…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址: https://leetcode.com/problems/number-of-atoms/description/ 题目描述: Given a chemical formula (given as a string), return the count of each atom. An atomic element always starts with an upperc…

Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to find the number of connected components in an undirected graph. Example 1: 0          3 |          | 1 --- 2    4 Given n = 5 and…

Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n. For example: Given n = 13, Return 6, because digit 1 occurred in the following numbers: 1, 10, 11, 12, 13. Hint: Beware of overflow.…

Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water. Count the number of distinct island…