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 ...

对于一个长度为n+1的数组，其中每一个值的取值范围是[1,n]，可以证明的是必然存在一个重复数字（抽屉原理），假设仅存在一个重复数字，找到他。 举例：输入：[1,3,4,2,1]，输出：1 自己做的时候，要么时间复杂度到o(n2)，要么需要额外的存储空间利用hashset，下面来分析一下 ...

287. 寻找重复数 这题的难点就在于下面的说明了，我们先不管下面的那些说明的要求，用常规的解法来解答下上的题目。 排序思想解法 先把原来的数组进行排序，然后逐个遍历，一旦发现后一个元素和当前的元素相等，那么就返回，这就是我们找到了重复数字。但是这种思想，就不满足说明里面的，不能改变原 ...

Given a binary tree, return all duplicate subtrees. For each kind of duplicate subtrees, you only need to return the root node of any oneof ...

Given a list of directory info including directory path, and all the files with contents in this directory, you need to find out all the groups ...

Write a SQL query to find all duplicate emails in a table named Person. For example, your query should return the following for the above table ...

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice ...

Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest Id. ...