【强连通分量】 HDOJ 4985 Little Pony and Permutation

求一下强连通分量就行。。。

#include <iostream>  
#include <queue>  
#include <stack>  
#include <map>  
#include <set>  
#include <bitset>  
#include <cstdio>  
#include <algorithm>  
#include <cstring>  
#include <climits>  
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 100005
#define maxm 300005
#define eps 1e-10
#define mod 1000000007
#define INF 999999999
#define lowbit(x) (x&(-x))
#define mp mark_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid  
#define rson o<<1 | 1, mid+1, R
#pragma comment(linker, "/STACK:16777216")  
typedef long long LL;
//typedef int LL;
using namespace std;
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}
// head

int h[maxn], next[maxm], v[maxm];
int dfn[maxn], low[maxn], ins[maxn];
int p[maxn], cnt, res, top, n, x;
stack<int> s;

void init(void)
{
	cnt = top = 0;
	memset(h, -1, sizeof h);
	memset(dfn, 0, sizeof dfn);
	memset(low, 0, sizeof low);
}
void addedges(int u, int vv)
{
	next[cnt] = h[u], h[u] = cnt, v[cnt] = vv, cnt++;
}
void tarjan(int u)  
{  
    dfn[u] = low[u] = ++top;  
    s.push(u), ins[u] = 1;  
    for(int e = h[u]; ~e; e = next[e]) {  
        if(!dfn[v[e]]) {  
            tarjan(v[e]);  
            low[u] = min(low[u], low[v[e]]);  
        }  
        else if(ins[v[e]]) low[u] = min(low[u], dfn[v[e]]);  
    }  
    if(dfn[u] == low[u]) {  
        int tmp = s.top(); s.pop(), ins[tmp] = 0;
		while(tmp != u) {
			p[res++] = tmp;
			tmp = s.top(); s.pop(), ins[tmp] = 0;
		}
		p[res++] = tmp;
		printf("(");
		for(int i = res-1; i >= 1; i--) printf("%d ", p[i]);
		printf("%d)", p[0]);
    }  
}
int main(void)
{
	while(scanf("%d", &n)!=EOF) {
		init();
		for(int i = 1; i <= n; i++) scanf("%d", &x), addedges(i, x);
		for(int i = 1; i <= n; i++) if(!dfn[i]) res = 0, tarjan(i);
		printf("\n");
	}
	return 0;
}