题意: 有一个含有n+1个元素的数组,元素值是在1-n之间的整数,请找出其中出现超过1次的数.(保证仅有1个出现次数是超过1的数) 思路: 方法一:O(nlogn).根据鸽笼原理及题意,每次如果<=k的数超过了k个,那么答案必定在[1,k].可以用二分枚举答案来解决. bool left(vector<int>& nums,int tar)//是否在左边 { ; ; i<nums.size(); i++) if(nums[i]<=tar) cnt++; return…

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k. Example 1: Input: nums = [1,2,3,1], k = 3 Output:…

Given an array of integers, find out whether there are two distinct indices i and j in the array such that the absolute difference between nums[i] and nums[j] is at most t and the absolute difference between i and j is at most k. Example 1: Input: nu…

［抄题］: 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. Example 1: Input: [1,3…

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…

Description: 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…

最容易想到的思路是新开一个长度为n的全零list p[1~n].依次从nums里读出数据,假设读出的是4, 就将p[4]从零改成1.如果发现已经是1了,那么这个4就已经出现过了,所以他就是重复的那个数.这个解法的时间复杂度是O(N).但是由于本题要求空间复杂度是O(1).所以不能用. 可以用二分法,low = 1, high = n, mid = (left + right)//2,如果<=mid 的元素个数 > mid,那么重复的数字一定在[1, mid]区间内.反之,则一定在[mid+1,…

10.6 You have 10 billion URLs. How do you detect the duplicate documents? In this case, assume that "duplicate" means that the URLs are identical. 这道题让我们在一百亿个URL链接中寻找相同项,看这数据量简直吓尿了,如果每个URL链接平均100个字符的话,每个字符是4个字节,那么总共需要占4TB的空间,我们无法在内存中导入这么大的数据量.假如…

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…

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct. 题目标签:Array, Hash Table 题目给了我们一个nums arr…

题目标签: 题目给了我们一个 email 的表格,让我们删除重复的. 建立Person p1,Person p2,当email 相同时,而且 p1 id 要大于 p2 id 时候,删除这一行. Java Solution: Runtime:  869 ms, faster than 33 % Memory Usage: N/A 完成日期:06/01/2019 关键点:p1.Id > p2.Id # Write your MySQL query statement below DELETE p1…

每天一算:Contains Duplicate II 描述 给出1个整形数组nums和1个整数k,是否存在索引i和j,使得nums[i] == nums[j] 且i和j之间的差不超过k Example 1: Input: nums = [1,2,3,1], k = 3 Output: true. Example 2: Input: nums = [1,0,1,1], k = 1 Output: true Example 3: Input: nums = [1,2,3,1,2,3], k = 2…

核心思想是:序列化树 序列化后,用String可以唯一的代表一棵树,其实就是前序遍历改造一下(空节点用符号表示): 一边序列化,一边用哈希表记录有没有重复的,如果有就添加,注意不能重复添加. 重点就是序列化树,序列化得到的String可以唯一的代表一棵树,这个思想很多题都用到了 并不是只是前序遍历就能唯一表示一棵树,加上结构信息就可以了. Map<String,TreeNode> map = new HashMap<>(); List<TreeNode> res = n…

题目描述 Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward. Example 1: Input: 121 Output: true Example 2: Input: -121 Output: false Explanation: From left to right, it reads -121. From rig…

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct. Example 1: Input: [1,2,3,1] Output: tru…

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…

LeetCode 287. Find the Duplicate Number 暴力解法 时间 O(nlog(n)),空间O(n),按题目中Note"只用O(1)的空间",照理是过不了的,但是可能判题并没有卡空间复杂度,所以也能AC. class Solution: # 基本思路为,将第一次出现的数字 def findDuplicate(self, nums: List[int]) -> int: s = set() for i in nums: a = i in s if a…

Leetcode之二分法专题-287. 寻找重复数(Find the Duplicate Number) 给定一个包含 n + 1 个整数的数组 nums,其数字都在 1 到 n 之间(包括 1 和 n),可知至少存在一个重复的整数.假设只有一个重复的整数,找出这个重复的数. 示例 1: 输入: [1,3,4,2,2] 输出: 2 示例 2: 输入: [3,1,3,4,2] 输出: 3 说明: 不能更改原数组(假设数组是只读的). 只能使用额外的 O(1) 的空间. 时间复杂度小于 O(n2)…

Given an array of integers, find out whether there are two distinct indices i and j in the array such that the difference between nums[i] and nums[j] is at most t and the difference between i and j is at most k. 这道题跟之前两道Contains Duplicate 包含重复值和Conta…

问题描述: 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 mod…

后面3个题都是限制在1-n的,所有可以不先排序,可以利用巧方法做.最后两个题几乎一模一样. 217. Contains Duplicate class Solution { public: bool containsDuplicate(vector<int>& nums) { int length = nums.size(); ) return false; sort(nums.begin(),nums.end()); ;i < length;i++){ ]) return tr…

题目 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…

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. Example 1: Input: [1,3,4,2,2…

传送门 Description 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 mu…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 保存已经访问过的数字 链表成环 二分查找 日期 题目地址:https://leetcode.com/problems/find-the-duplicate-number/description/ 题目描述 Given an array nums containing n + 1 integers where each integer is betwe…

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…

Difficulty:medium  More:[目录]LeetCode Java实现 Description 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 numbe…

Level:   Medium 题目描述: 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. Exampl…

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…

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. Example 1: Input: [1,3,4,2,2…