CF844 C 置换 水

由于每个数字只出现一次，离散化一下，置换求个循环节就好了。

/** @Date    : 2017-08-25 01:39:39

  * @FileName: C.cpp

  * @Platform: Windows

  * @Author  : Lweleth ([email protected])

  * @Link    : https://github.com/

  * @Version : $Id$

  */

#include <bits/stdc++.h>

#define LL long long

#define PII pair<int ,int>

#define MP(x, y) make_pair((x),(y))

#define fi first

#define se second

#define PB(x) push_back((x))

#define MMG(x) memset((x), -1,sizeof(x))

#define MMF(x) memset((x),0,sizeof(x))

#define MMI(x) memset((x), INF, sizeof(x))

using namespace std;

const int INF = 0x3f3f3f3f;

const int N = 2e5+20;

const double eps = 1e-8;

int a[N];

int pos[N];

vector<int>q[N];

int vis[N];

int main()

{

	int n;

	while(cin >> n)

	{

		MMF(vis);

		MMF(pos);

		map<int,int>s;

		for(int i = 1; i <= n; i++)

			scanf("%d", a + i), pos[i] = a[i];

		sort(a + 1, a + n + 1);

		for(int i = 1; i <= n; i++)

			s[a[i]] = i;

		for(int i = 1; i <= n; i++)

			a[i] = s[pos[i]];

		int c = 0;

		for(int i = 1; i <= n; i++)

		{

			if(!vis[a[i]] && a[i] != i)

			{

				int cnt = 2;

				int np = a[i];

				vis[i] = 1;

 				while(a[np] != i || !vis[i])

				{

					cnt++;

					vis[np] = 1;

					q[c].PB(np);

					np = a[np];

				}

				vis[np] = 1;

				q[c].PB(np);

				q[c].PB(i);

				c++;

			}

			else if(a[i] == i)

			{

				q[c++].PB(a[i]);

				vis[i] = 1;

			}

		}

		printf("%d\n", c);

		for(int i = 0; i < c; i++)

		{

			printf("%d", q[i].size());

			while(!q[i].empty())

			{

				printf(" %d", q[i].back());

				q[i].pop_back();

			}

			printf("\n");

		}

	}

    return 0;

}