You are given a 0-indexed integer array nums of length n.
The average difference of the index i is the absolute difference between the average of the first i + 1 elements of nums and the average of the last n - i - 1 elements. Both averages should be rounded down to the nearest integer.
Given a string s, sort it in decreasing order based on the frequency of the characters. The frequency of a character is the number of times it appears in the string.
今天在刷題的時候，看到一位分享自己解題思路的網友，他的程式碼中所有宣告的 vector 陣列，全部都使用 emplace_back()。那時候我可看不明白了，從我在大學上課開始寫時，老師都是教寫 push_back() 的啊？
You are given an integer array matches where matches[i] = [winneri, loseri] indicates that the player winneri defeated player loseri in a match.
Given an integer array nums, return the number of all the arithmetic subsequences of nums.
ou are given two strings s and t consisting of only lowercase English letters.
Return the minimum number of characters that need to be appended to the end of s so that t becomes a subsequence of s.
Given a positive integer n, find the pivot integer x such that:
1 and x inclusively equals the sum of all elements between x and n inclusively. Given an m x n grid of characters board and a string word, return true if word exists in the grid.