目录 题目链接 注意点 解法 小结 题目链接 Letter Combinations of a Phone Number - LeetCode 注意点 可以不用按字典序排序 解法 解法一:输入的数字逐个处理,在已经生成的字符串后面追加该当前数字对应的所有字符.时间复杂度为O(n) class Solution { public: vector<string> letterCombinations(string digits) { vector<string> ans,temp_an…

目录 题目链接 注意点 解法 小结 题目链接 Palindrome Number - LeetCode 注意点 负数肯定是要return false的 数字的位数要分奇数和偶数两种情况 解法 解法一:将数字转化为字符串,然后对字符串从中间开始往两边拓展比较,要分长度为奇数和偶数的情况.时间复杂度为O(n) class Solution { public: bool isPalindrome(int x) { if(x<0 || (x%10 == 0 && x!=0)) { retur…

examination questions Write an algorithm to determine if a number is "happy". A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat…

Write an algorithm to determine if a number is "happy". A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the…

题目: Given a digit string, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on the telephone buttons) is given below. Input:Digit string "23" Output: ["ad", "ae"…

Given a list of non negative integers, arrange them such that they form the largest number. For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330. Note: The result may be very large, so you need to return a string instead of an i…

Given a digit string, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on the telephone buttons) is given below. Input:Digit string "23" Output: ["ad", "ae", &q…

问题描述: Write a program to check whether a given number is an ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7. Note that 1…

问题描述: Given an array of integers, every element appears twice except for one. Find that single one. Note:Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? 要求:采用线性时间复杂度,并且最好不使用多余的空间. 一.位操作 异或运算,…

题目: Determine whether an integer is a palindrome. Do this without extra space. click to show spoilers. Some hints: Could negative integers be palindromes? (ie, -1) If you are thinking of converting the integer to string, note the restriction of using…

Write a program to find the nth super ugly number. Super ugly numbers are positive numbers whose all prime factors are in the given prime list primes of size k. For example, [1, 2, 4, 7, 8, 13, 14, 16, 19, 26, 28, 32] is the sequence of the first 12…

A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down). Write a function to determine if a number is strobogrammatic. The number is represented as a string. For example, the numbers "69", "…

Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate number must exist. Assume that there is only one duplicate number, find the duplicate one. Note: You must not modify th…

Question 136. Single Number Solution 思路:构造一个map,遍历数组记录每个数出现的次数,再遍历map,取出出现次数为1的num public int singleNumber(int[] nums) { Map<Integer, Integer> countMap = new HashMap<>(); for (int i=0; i<nums.length; i++) { Integer count = countMap.get(nums…

很简单的26进制问题 int titleToNumber(char* s) { int sum=0,temp; char *p=s; while(*p!='\0'){ sum=sum*26+(*p-'A'+1); p++; } return sum; }…

#include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX 1000 int cmp(char *s1,char *s2){ ]; ]; strcpy(temp1,s1); strcat(temp1,s2); strcpy(temp2,s2); strcat(temp2,s1); ); ; } char* into_string(int n){ char *p; p=(*sizeof(ch…

Determine whether an integer is a palindrome. Do this without extra space. Some hints: Could negative integers be palindromes? (ie, -1) If you are thinking of converting the integer to string, note the restriction of using extra space. You could also…

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 usi…

Given an array of integers, every element appears twice except for one. Find that single one. Note:Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? Subscribe to see which companies asked this…

从十月份开始到现在,差不多近3个月时间吧. 中间有的时候有事没有办法刷题,也有的题目比较难,比较麻烦,会浪费很多时间,71道题,也都是简单的. 下图是最后20道刷题的记录吧. 完成自己的目标是轻松的. 之后会减慢刷题的节奏,也要做做总结.毕竟还有别的事情要做.…

题目: Validate if a given string is numeric. Some examples: "0" => true " 0.1 " => true "abc" => false "1 a" => false "2e10" => true Note: It is intended for the problem statement to be ambigu…

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. class Solution(object): def missingNumber(self, nums): """ :type nums: List[i…

June 22, 2015 Given a number represented as an array of digits, plus one to the number. Leetcode: plus one, 喜欢这道题, 看看有哪些解法; 一个个试过来. (6种方法) Read the web blogs, and then, try different solutions. practice using C#, the source code on github: https://gi…

最近在准备找工作的算法题,刷刷LeetCode,以下是我的解题报告索引,每一题几乎都有详细的说明,供各位码农参考.根据我自己做的进度持续更新中......                              本文地址 LeetCode:Reverse Words in a String LeetCode:Evaluate Reverse Polish Notation LeetCode:Max Points on a Line LeetCode:Sort List LeetCode:Ins…

LeetCode专题-Python实现之第1题:Two Sum LeetCode专题-Python实现之第7题:Reverse Integer LeetCode专题-Python实现之第9题:Palindrome Number LeetCode专题-Python实现之第13题:Roman to Integer LeetCode专题-Python实现之第14题:Longest Common Prefix LeetCode专题-Python实现之第20题:Valid Parentheses Leet…

Here is my collection of solutions to leetcode problems. Related code can be found in this repo: https://github.com/zhuli19901106/leetcode LeetCode - Course Schedule LeetCode - Reverse Linked List LeetCode - Isomorphic Strings LeetCode - Count Primes…

There are a number of spherical balloons spread in two-dimensional space. For each balloon, provided input is the start and end coordinates of the horizontal diameter. Since it's horizontal, y-coordinates don't matter and hence the x-coordinates of s…

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 matters). Find the number of boomerangs.…

Count the number of segments in a string, where a segment is defined to be a contiguous sequence of non-space characters. Please note that the string does not contain any non-printable characters. Example: Input: "Hello, my name is John" Output:…

Given a non-empty array of integers, return the third maximum number in this array. If it does not exist, return the maximum number. The time complexity must be in O(n). Example 1: Input: [3, 2, 1] Output: 1 Explanation: The third maximum is 1. Examp…