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;
}