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思路如下：先把数组从小到大排序，然后依次遍历数组，当前index为i，前0到i-1个数字的和为s，则剩余的值为target-s，假如当前arr[i]*(len(arr)-i)已经大于target-s了，则说明可以从当前第i个值开始，将所有之后的值均设置为同一个值，来逼近target，如果小于target-s，则说明即使从当前第i个值开始，将所有之后的值都设置为同一个值，也依旧会小于target，不是最优解。当大于target-s，则需要有一个边界判断，mean=target-s/(len(arr)-i),

题目Two elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure. Note: A solution using O(n) space is pretty straight forward. Could you devise a c

题目Find the length of the longest substring T of a given string (consists of lowercase letters only) such that every character in T appears no less than k times.Example 1:Input:s = "aaabb", k = 3Output

题目Given a char array representing tasks CPU need to do. It contains capital letters A to Z where different letters represent different tasks.Tasks could be done without original order. Each task could

题目Implement the following operations of a stack using queues.push(x) -- Push element x onto stack.pop() -- Removes the element on top of the stack.top() -- Get the top element.empty() -- Return whet

A magical string S consists of only ‘1’ and ‘2’ and obeys the following rules:The string S is magical because concatenating the number of contiguous occurrences of characters ‘1’ and ‘2’ generates the

题目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：题目的意思就是判断

Given an unsorted array, find the maximum difference between the successive elements in its sorted form.Try to solve it in linear time/space.Return 0 if the array contains less than 2 elements.You may

题目Sort a linked list using insertion sort.解法用插入排序对链表进行排序。遍历链表，每次将当前结点插入到已经排序好的列表。代码/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(