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A. ReverseYou are given a permutation p1,p2,…,pn of length n. You have to choose two integers l,r (1≤l≤r≤n) and reverse the subsegment [l,r] of the permutation. The permutation will become p1,p2,…,pl−1,pr,pr−1,…,pl,pr+1,pr+2,…,pn.Find the lexicographical

得到 0 的操作数给你两个 非负 整数 num1 和 num2 。每一步 操作 中，如果 num1 >= num2 ，你必须用 num1 减 num2 ；否则，你必须用 num2 减 num1 。例如，num1 = 5 且 num2 = 4 ，应该用 num1 减 num2 ，因此，得到 num1 = 1 和 num2 = 4 。然而，如果 num1 = 4且 num2 = 5 ，一步操作后，得到 num1 = 4 和 num2 = 1 。返回使 num1 = 0 或 num2 = 0 的 操

A. Sorting PartsYou have an array a of length n. You can exactly once select an integer len between 1 and n−1 inclusively, and then sort in non-decreasing order the prefix of the array of length len and the suffix of the array of length n−lenFor example,

A. Rainbow Dash, Fluttershy and Chess Coloring time limit per test 1 second memory limit per test 256 megabytes input

A. Div. 7题目：You are given an integer n. You have to change the minimum number of digits in it in such a way that the resulting number does not have any leading zeroes and is divisible by 7.If there are multiple ways to do it, print any of them. If the g