CSU 1526 Beam Me out! Strong connectivity

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Test instructions

A direction graph for a given n points (1 is the starting point and N is the end point)

Each of the following lines gives the degree of a point and the next point to which it is connected.

The nth point is not out of the degree

The picture is like this: 1->2, 1->3, 2->3

First question:

If there is a scheme that allows this person to enter a point and no longer reach the end of the output PRISON, otherwise the output pardon

Second question:

If this person can walk infinite steps in the diagram output unlimited, otherwise the output limited

#include <iostream> #include <cstdio> #include <algorithm> #include <string> #include <cmath > #include <cstring> #include <queue> #include <set> #include <map> #include <vector> Template <class t>inline BOOL Rd (T &ret) {char c; int sgn;if (c = GetChar (), c = = EOF) return 0;while (c! = '-') && (c< ' 0 ' | | c> ' 9 ')) C = GetChar (); sgn = (c = = '-')? -1:1;ret = (c = = '-')? 0: (C-' 0 '); while (c = GetChar (), C >= ' 0 ' &&c <= ' 9 ') ret = ret * + (C-' 0 '); ret *= Sgn;return 1;} Template <class t>inline void pt (T x) {if (x <0) {Putchar ('-'); x = x;} if (x>9) pt (X/10);p Utchar (x% 10 + ' 0 ');} Using namespace Std;typedef long Long ll;typedef pair<int, int> pii;const int N = 50500;const int inf = 1e8;//n is the maximum number of points const int M = 7500000;//m is the maximum number of sides int n;//n M is the number of points and sides of the struct edge{int from, to, Nex;bool sign;//is the bridge}edge[m];int Head[n], Edgenu m;void Add (int u, int v) {//the start and end point of the Edge E = {u, V, head[u], false};Edge[edgenum] = e;head[u] = edgenum++;} int dfn[n], low[n], Stack[n], top, time; Low[u] is the dfn[v of the point set {U-point and subtree in the root of the U-point (all reverse arcs) can be pointed (that is, the nearest ancestor V from the root) value (i.e. V-point timestamp) int taj;//Connected Branch label, starting from 1 int belong[n];//belong[i] Indicates that I point belongs to the connected branch bool Instack[n];vector<int> Bcc[n]; Marking starting from 1 void Tarjan (int u, int fa) {Dfn[u] = low[u] = ++time; stack[top++] = U;instack[u] = 1;for (int i = head[u]; ~i; i = edge[i].nex) {int v = edge[i].to;if (dfn[v] = =-1) {Tarjan (V, u); Low[u] = min (Low[u], low[v]), if (Dfn[u] < Low[v]) {edge[i].sign = 1;//for Cut bridge}}else if (Instack[v]) low[u] = min (Low[u], DFN [v]);} if (low[u] = = Dfn[u]) {int now;taj++; Bcc[taj].clear ();d O{now = Stack[--top];instack[now] = 0; Belong[now] = Taj;bcc[taj].push_back (now);} while (now! = u);}}  void Tarjan_init (int all) {memset (DFN,-1, sizeof (DFN)), memset (instack, 0, sizeof (instack)), top = time = Taj = 0;for (int i = 1; I <= all; i++) if (dfn[i] = =-1) Tarjan (i, I); Notice the start point!!! }vector<int>g[n];int Du[n], Hehe[n];bool itself[n];void Suodian () {memset (Du, 0, sizeof (du)); foR (int i = 1; I <= Taj; i++) {g[i].clear (); Hehe[i] = false;for (int j = 0; J < Bcc[i].size (), j + +) if (itself[bcc[i][j ]]) hehe[i] = true;} for (int i = 0; i < Edgenum; i++) {int u = belong[edge[i].from], v = belong[edge[i].to];if (U = v) g[u].push_back (v), Du [V]++;}} void Init () {memset (head,-1, sizeof (head)); edgenum = 0;} BOOL Vis[n];int siz, Bad;void bfs () {memset (Vis, 0, sizeof vis);queue<int> Q; Q.push (belong[1]); vis[belong[1]] = Tru E;siz = 0;bad = 0;while (!q.empty ()) {int u = q.front (); Q.pop ()//printf ("--%d\n", u); if ((int) bcc[u].size () > 1 | | he He[u]) siz++;if ((int) g[u].size () = = 0) {if (U! = belong[n]) bad++;} for (int i = 0; i < g[u].size (); i++) {int v = g[u][i];//printf ("**%d\n", V), if (!vis[v]) {Vis[v] = True;q.push (v);}} }int Main () {while (CIN >> N) {init (); for (int i = 1, num, j; i < n; i++) {Itself[i] = false;rd (num); while (num--& gt;0) {Rd (J), Add (i, J), if (j = = i) itself[i] = true;}} Itself[n] = False;tarjan_init (n); Suodian ();//for (int i = 1; i <= N; i++) printf ("%d", belong[i]); Puts (""); BFS ("");//printf ("leaf:%d siz:%d\n", Leaf, siz); if (Vis[belong[n]] && bad = = 0) printf ("pardon"); else pri NTF ("PRISON");! Siz? Puts ("LIMITED"): Puts ("UNLIMITED");} return 0;} /*3213*/

CSU 1526 Beam Me out! Strong connectivity