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? 题目分析:数字每一位存在数组中,每个数字承兑出现,只有一个数字只出现一次,我们知道异或运…
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…
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…
203. Remove Linked List Elements[easy] Remove all elements from a linked list of integers that have value val. ExampleGiven: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6Return: 1 --> 2 --> 3 --> 4 --> 5 Credits:Special than…
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…
167. Two Sum II - Input array is sorted[easy] Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such…
283. Move Zeroes[easy] Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements. For example, given nums = [0, 1, 0, 3, 12], after calling your function, nums should be [1, 3…
344. Reverse String[easy] Write a function that takes a string as input and returns the string reversed. Example:Given s = "hello", return "olleh". 解法一: class Solution { public: string reverseString(string s) { , end = s.length() - ; w…
557. Reverse Words in a String III[easy] Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order. Example 1: Input: "Let's take LeetCode contest" Output:…
2. Trailing Zeros[easy] Write an algorithm which computes the number of trailing zeros in n factorial. Have you met this question in a real interview? Yes Example 11! = 39916800, so the out should be 2 Challenge O(log N) time 解法一: class Solution { /*…
181. Flip Bits[easy] Determine the number of bits required to flip if you want to convert integer n to integer m. Notice Both n and m are 32-bit integers. Example Given n = 31 (11111), m = 14 (01110), return 2. 解法一: class Solution { public: /** *@par…
14. First Position of Target [easy] For a given sorted array (ascending order) and a targetnumber, find the first index of this number in O(log n) time complexity. If the target number does not exist in the array, return -1. Example If the array is […
28. Search a 2D Matrix [easy] Write an efficient algorithm that searches for a value in an mx n matrix. This matrix has the following properties: Integers in each row are sorted from left to right. The first integer of each row is greater than the la…
60. Search Insert Position [easy] Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order. You may assume NO duplicates in the array. Example [1,3,5,6],…
hdu 6216 A Cubic number and A Cubic Number[数学] 题意:判断一个素数是否是两个立方数之差,就是验差分.. 题解:只有相邻两立方数之差才可能,,因为x^3-y^3=(x-y)(x^2+xy+y^2),看(x-y),就能很快想到不相邻的立方数之差是不可能是素数的:),,然后把y=x+1代入,得:p=3x^2+3x+1,所以可得判断条件为:①p-1必须能被3整除:②(p-1)/3必须能表示为两个相邻整数之积. #include<iostream> #inc…
160. Intersection of Two Linked Lists[easy] Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: A: a1 → a2 ↘ c1 → c2 → c3 ↗ B: b1 → b2 → b3 begin to intersect at n…
206. Reverse Linked List[easy] Reverse a singly linked list. Hint: A linked list can be reversed either iteratively or recursively. Could you implement both? 解法一: class Solution { public: ListNode* reverseList(ListNode* head) { ListNode * pre = NULL;…
83. Remove Duplicates from Sorted List[easy] Given a sorted linked list, delete all duplicates such that each element appear only once. For example,Given 1->1->2, return 1->2.Given 1->1->2->3->3, return 1->2->3. 解法一: /** * Defin…
21. Merge Two Sorted Lists[easy] Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. 解法一: /** * Definition for singly-linked list. * struct ListNode { * int val…
142. Linked List Cycle II[easy] Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Note: Do not modify the linked list. Follow up:Can you solve it without using extra space? 解法一: /** * Definition for singl…
141. Linked List Cycle[easy] Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? 解法一: /** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x…
237. Delete Node in a Linked List[easy] Write a function to delete a node (except the tail) in a singly linked list, given only access to that node. Supposed the linked list is 1 -> 2 -> 3 -> 4 and you are given the third node with value 3, the l…
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…
121. Best Time to Buy and Sell Stock[easy] Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an…
661. Image Smoother[easy] Given a 2D integer matrix M representing the gray scale of an image, you need to design a smoother to make the gray scale of each cell becomes the average gray scale (rounding down) of all the 8 surrounding cells and itself.…
27. Remove Element[easy] Given an array and a value, remove all instances of that value in place and return the new length. Do not allocate extra space for another array, you must do this in place with constant memory. The order of elements can be ch…
26. Remove Duplicates from Sorted Array[easy] Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length. Do not allocate extra space for another array, you must do this in place with consta…
