HDU 3849 by recognizing these Guys, We Find social Networks useful (dual connectivity)

HDU 3849 by recognizing these Guys, We Find social Networks useful

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Test instructions: It's plain to ask for a bridge without a map

Idea: string hash out, then double connect. Pay attention to a special sentence. The hypothesis is not a connected block. So the answer is 0.

Code:

#include <cstdio> #include <cstring> #include <string> #include <vector> #include <map> using namespace Std;const int N = 10005;const int M = 200005;int T, N, m;map<string, int> Hash;char a[20], b[20];str UCT Edge {int u, V, Id;bool iscut; Edge () {}edge (int u, int v, int id) {this->u = U;this->v = V;this->id = Id;this->iscut = false;}} Edge[m];int en, First[n], next[m], Hn;char name[n][20];void init () {en = HN = 0;memset (First,-1, sizeof (first)); Hash.clea R ();} int get (char *str) {if (!hash.count (str)) {strcpy (Name[hn], str); HASH[STR] = hn++;} return HASH[STR];} void Add_edge (int u, int v, int id) {Edge[en] = Edge (U, V, id); Next[en] = first[u];first[u] = en++;} int pre[n], dfn[n], dfs_clock, ans = 0;void dfs_cut (int u, int f) {pre[u] = Dfn[u] = ++dfs_clock;for (int i = first[u]; I + 1; i = Next[i]) {if (edge[i].id = = f) Continue;int v = edge[i].v;if (!pre[v]) {dfs_cut (V, edge[i].id);d fn[u] = min (Dfn[u], DF N[V]), if (Dfn[v] > Pre[u]) {Ans++;edge[i]. Iscut = Edge[i^1].iscut = true;}} else Dfn[u] = min (Dfn[u], pre[v]);}} void Find_cut () {memset (pre, 0, sizeof (PRE)), for (int i = 0; i < n; i++) if (!pre[i]) dfs_cut (i,-1);} int parent[n];int Find (int x) {return parent[x] = = x?
X:PARENT[X] = find (Parent[x]);}  int main () {scanf ("%d", &t), while (t--) {init (); scanf ("%d%d", &n, &m); for (int i = 0; i < n; i++) Parent[i] = I;int cnt = n;for (int i = 0; i < m; i++) {scanf ("%s%s", A, B), int u = Get (a), V = Get (B), Add_edge (U, V, i); Add_edge (V, U, i); int pu = find (u), PV = Find (v), if (pu! = PV) {cnt--;p arent[pu] = PV;}} if (CNT > 1) {printf ("0\n"); continue;} ans = 0;find_cut ();p rintf ("%d\n", ans); for (int i = 0; i < en; i + = 2) if (edge[i].iscut) printf ("%s%s\n", Name[edge[i] . u], name[edge[i].v]);} return 0;}

HDU 3849 by recognizing these Guys, We Find social Networks useful (dual connectivity)