Check a positive number is a palindrome or not. A palindrome number is that if you reverse the whole number you will get exactly the same number. Notice It's guaranteed the input number is a 32-bit integer, but after reversion, the number may exceed…

680. Valid Palindrome II[easy] Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome. Example 1: Input: "aba" Output: True Example 2: Input: "abca" Output: True Explanation: You co…

Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome. Example 1: Input: "aba" Output: True Example 2: Input: "abca" Output: True Explanation: You could delete the character 'c'. N…

Given 2*n + 1 numbers, every numbers occurs twice except one, find it.   Example Given [1,2,2,1,3,4,3], return 4 Challenge One-pass, constant extra space. 题意 给出2*n + 1 个的数字,除其中一个数字之外其他每个数字均出现两次,找到这个数字. 解法一: class Solution { public: /* * @param A: An…

234. Palindrome Linked List[easy] Given a singly linked list, determine if it is a palindrome. Follow up:Could you do it in O(n) time and O(1) space? 解法一: /** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * Lis…

125. Valid Palindrome[easy] Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example,"A man, a plan, a canal: Panama" is a palindrome."race a car" is not a palindrome. No…

170. Two Sum III - Data structure design[easy] Design and implement a TwoSum class. It should support the following operations:add and find. add - Add the number to an internal data structure.find - Find if there exists any pair of numbers which sum…

88. Merge Sorted Array[easy] Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array. Note:You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2.…

605. Can Place Flowers[easy] Suppose you have a long flowerbed in which some of the plots are planted and some are not. However, flowers cannot be planted in adjacent plots - they would compete for water and both would die. Given a flowerbed (represe…

485. Max Consecutive Ones[easy] Given a binary array, find the maximum number of consecutive 1s in this array. Example 1: Input: [1,1,0,1,1,1] Output: 3 Explanation: The first two digits or the last three digits are consecutive 1s. The maximum number…