还是贴一份tarjan的代码吧 ，QwQ
1 #include <algorithm> 2 #include <iostream> 3 #include <cstdlib> 4 #include <cstring> 6 #include <cstdio> 7 #include <vector> 8 #include <queue> 9 using namespace std ; 10 const int inf = 1 << 30 , maxn = 10000 + 100 , maxe = 500000 + 100 ; 11 int n , m , cnt ,head[maxn] , tot , top , sta[maxn], dfn[maxn] , low[maxn] , sum[maxn]; 12 struct id { 13 int to , nxt ; 14 } edge[maxe] ; 15 bool lie[maxe] ; 16 vector< vector<int> > node( maxn ) ; 17 18 19 inline void Init( ) { 20 freopen( "10717.in" , "r" , stdin ) ; 21 freopen( "10717.out" , "w" , stdout ) ; 22 } 23 24 int read( ) { 25 char ch = getchar( ) ; int ret = 0 , k = 1 ; 26 while( ch < '0' || ch > '9' ) { if( ch == '-' ) k = -1 ; ch = getchar( ) ; } 27 while( ch >= '0' && ch <= '9' ) ret = ret * 10 + ch - '0' , ch = getchar( ) ; 28 return ret * k ; 29 } 30 31 32 void add( int u , int v ) { 33 edge[++cnt].to = v ; 34 edge[cnt].nxt = head[u] ; 35 head[u] = cnt ; 36 } 37 38 39 void input( ) { 40 n = read( ) , m = read( ) ; 41 int u , v ; 42 memset( head , -1 , sizeof( head ) ) ; 43 for( int x = 1 ; x <= m ; ++x ) { 44 u = read( ) , v = read( ) ; 45 add( u , v ) ; 46 } 47 cnt = 0 ; 48 } 49 50 51 void scc( int u ) { 52 dfn[u] = ++tot ; low[u] = tot ; 53 sta[++top] = u ; lie[u] = true ; 54 for( int i = head[u] ; ~i ; i = edge[i].nxt ) { 55 int v = edge[i].to ; 56 if( dfn[v] == 0 ) 57 { 58 scc( v ) ; 59 low[u] = min( low[u] , low[v] ) ; 60 } 61 else if( lie[v] ) { 62 low[u] = min( low[u] , dfn[v] ) ; 63 } 64 } 65 if( low[u] == dfn[u] ) { 66 cnt ++ ; 67 int front = 0 ; 68 do { 69 front = sta[top--] ; 70 sum[cnt] ++ ; 71 node[cnt].push_back( front ) ; 72 lie[front] = false ; 73 74 } while( front != u ) ; 75 } 76 } 77 78 79 80 void sov( ) { 81 for( int x = 1 ; x <= n ; ++x ) { 82 if( dfn[x] == 0 ) scc( x ) ; 83 } 84 } 85 86 87 88 void output( ) { 89 printf( "%d " , cnt ) ; 90 for( int x = 1 ; x <= cnt ; ++x ) { 91 printf( "%d " , sum[x] ) ; 92 for( int y = 0 ; y < sum[x] ; y++ ) 93 printf( "%d " , node[x][y] ) ; 94 printf( " " ) ; 95 } 96 } 97 98 99 int main ( ) { 100 // Init( ) ; 101 input( ) ; 102 sov( ) ; 103 output( ) ; 104 // fclose( stdin ) ; 105 // fclose( stdout ) ; 106 return 0 ; 107 }