题目链接 \(Description\) 给定一个\(n\)的排列\(p_i\),求一个排列\(q_i\),使得对于任意\(1\leq i\leq n\),\(q_{q_i}=p_i\).无解输出\(-1\). \(1\leq n\leq10^6\). \(Solution\) 对排列\(q_i\)我们建一张图,边为\(i\to q_i\).显然这张图是由几个环构成. 发现对于\(q_{q_i}\)的图,原来\(q_i\)中的奇环它们还是类似的一个奇环,原来的偶环会分裂成两个大小相等的偶环. 所…

E. Square Root of Permutation A permutation of length n is an array containing each integer from 1 to n exactly once. For example, q = [4, 5, 1, 2, 3] is a permutation. For the permutation q the square of permutation is the permutation p that p[i] = …

A permutation of length n is an array containing each integer from 1 to n exactly once. For example, q = [4, 5, 1, 2, 3] is a permutation. For the permutation q the square of permutation is the permutation p that p[i] = q[q[i]] for each i = 1... n. F…

A permutation of length n is an array containing each integer from 1 to n exactly once. For example, q = [4, 5, 1, 2, 3] is a permutation. For the permutation q the square of permutation is the permutation p that p[i] = q[q[i]] for each i = 1... n. F…

Description A permutation of length n is an array containing each integer from 1 to n exactly once. For example, q = [4, 5, 1, 2, 3] is a permutation. For the permutation q the square of permutation is the permutation p that p[i] = q[q[i]] for each i…

题目分析 我们首先模拟一下题意 假设有一个 \(q _1\) \(p\) \(a_1\) \(a_x\) \(a_{a_1}\) \(a_{a_x}\) \(q\) \(x\) \(a_1\) \(a_x\) \(a_{a_1}\) \(pos\) 1 \(x\) \(a_1\) \(a_x\) 对这个表格分析,发现,当前节点的后继为前驱的对应 如果我们对 \(i \to p_i\) 建边,模拟一下,发现 偶环是会有两个环组成,而奇环会形成一个类似于五角星的图形 于是,我们可以找出所有环,对于奇…

A. Plus and Square Root time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output ZS the Coder is playing a game. There is a number displayed on the screen and there are two buttons, ' + ' (plus) an…

C. Plus and Square Root time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output ZS the Coder is playing a game. There is a number displayed on the screen and there are two buttons, ' + ' (plus) an…

A. Plus and Square Root 题目连接: http://codeforces.com/contest/715/problem/A Description ZS the Coder is playing a game. There is a number displayed on the screen and there are two buttons, ' + ' (plus) and '' (square root). Initially, the number 2 is d…

题目链接:Codeforces 417E Square Table 题目大意:给出n和m.要求给出一个矩阵,要求每一列每一行的元素的平方总和是一个平方数. 解题思路:构造.依照 a a a b a a a b a a a b c c c d 的方式取构造,然后a,b,c,d的值用随机生成数去枚举,只是我认为用暴力也是能够的. #include <cstdio> #include <cstring> #include <cmath> #include <cstdli…