HDU-置换群

问题及代码：

/*  
*Copyright (c)2014,烟台大学计算机与控制工程学院  
*All rights reserved.  
*文件名称：HDU.cpp  
*作    者：单昕昕  
*完成日期：2015年1月27日  
*版 本 号：v1.0  
*问题描述：As a unicorn, the ability of using magic is the distinguishing feature among other kind of pony. Being familiar with composition and decomposition is the fundamental course for a young unicorn. Twilight Sparkle is interested in the decomposition of permutations. A permutation of a set S = {1, 2, ..., n} is a bijection from S to itself. In the great magician —— Cauchy's two-line notation, one lists the elements of set S in the first row, and then for each element, writes its image under the permutation below it in the second row. For instance, a permutation of set {1, 2, 3, 4, 5} σ can be written as:


Here σ(1) = 2, σ(2) = 5, σ(3) = 4, σ(4) = 3, and σ(5) = 1.
Twilight Sparkle is going to decompose the permutation into some disjoint cycles. For instance, the above permutation can be rewritten as:


Help Twilight Sparkle find the lexicographic smallest solution. (Only considering numbers). 
*程序输入：Input contains multiple test cases (less than 10). For each test case, the first line contains one number n (1<=n<=10^5). The second line contains n numbers which the i-th of them(start from 1) is σ(i). 
*程序输出：For each case, output the corresponding result. 
Sample Input
5
2 5 4 3 1
3
1 2 3
Sample Output
(1 2 5)(3 4)
(1)(2)(3)
*/
#include
#include
#include
using namespace std;
const int MAX=100000;
int main()
{
    std::ios::sync_with_stdio(false);
    int n,i,j,k;
    int a[MAX];
    while(cin>>n)
    {
        for(i=1; i<=n; i++)
            cin>>a[i];
        for(i=1; i<=n; i++)
        {
            while(a[i])
            {
                cout<<"("<

运行结果：


知识点总结：
置换群。

学习心得：

就是按规律置换。