Topological sort/dfs hdoj 4324 Triangle Love

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Test instructions: Sentence triangle Love (ternary ring). If a likes B, then B must not like a, any two people must have a relationship connection

Analysis: The positive solution should be a topological sequencing of the ring, if there is a ring, must be ternary ring, proof. DFS: Search from any point, search for point markers, otherwise time out. See if there is a two-point distance difference equal to 2, if present, then the above triangle ring. other practices.

Harvest: DFS search must use the VIS array ah, otherwise it is easy to timeout

Code (topology Sort):

/************************************************* author:running_time* Created time:2015-8-25 19:24:24* File Na Me:E_topo.cpp ************************************************/#include <cstdio> #include <algorithm># Include <iostream> #include <sstream> #include <cstring> #include <cmath> #include <string > #include <vector> #include <queue> #include <deque> #include <stack> #include <list># Include <map> #include <set> #include <bitset> #include <cstdlib> #include <ctime>using namespace std; #define Lson L, Mid, RT << 1#define Rson mid + 1, R, RT << 1 | 1typedef long ll;const int N = 2e3 + 10;const int INF = 0x3f3f3f3f;const int MOD = 1e9 + 7;char s[n][n];vector<int    > G[n];int in[n];int n;bool topo_sort (void) {memset (in, 0, sizeof (in));    for (int i=1, i<=n; ++i) {for (int j=0; j<g[i].size (); ++j) in[g[i][j]]++; } queue<int> Q;    int cnt = 0;    for (int i=1; i<=n; ++i) if (!in[i]) Q.push (i); while (! Q.empty ()) {int u = q.front ();        Q.pop ();        cnt++;            for (int i=0; i<g[u].size (); ++i) {int v = g[u][i]; if (! (        --IN[V]) Q.push (v);    }} if (cnt = = N) return false; else return true;} int main (void) {int T, cas = 0;scanf ("%d", &t), while (t--) {scanf ("%d", &n), for (int i=1; i<=n; ++i) g[i        ].clear ();            for (int i=1; i<=n; ++i) {scanf ("%s", S[i] + 1);            for (int j=1; j<=n; ++j) {if (s[i][j] = = ' 1 ') G[i].push_back (j); }}printf ("Case #%d:%s\n", ++cas, (Topo_sort ()?    "Yes": "No");} return 0;}

Code (DFS):

/************************************************* author:running_time* Created time:2015-8-25 9:44:18* File Nam E:e.cpp ************************************************/#include <cstdio> #include <algorithm># Include <iostream> #include <sstream> #include <cstring> #include <cmath> #include <string > #include <vector> #include <queue> #include <deque> #include <stack> #include <list># Include <map> #include <set> #include <bitset> #include <cstdlib> #include <ctime>using namespace std; #define Lson L, Mid, RT << 1#define Rson mid + 1, R, RT << 1 | 1typedef long ll;const int N = 2e3 + 10;const int INF = 0x3f3f3f3f;const int MOD = 1e9 + 7;char s[n][n];bool vis[n];i NT D[n];int n;bool DFS (int u) {for (int i=1; i<=n; ++i) {if (s[u][i] = = ' 1 ') {if (Vis[i] &amp            ;& D[u] = = D[i] + 2) return true; else if (!vis[i]) {vis[i] = true;                D[i] = D[u] + 1;            if (DFS (i)) return true; }}} return false;} int main (void) {int T, cas = 0;scanf ("%d", &t), while (t--) {scanf ("%d", &n), memset (Vis, false, sizeof (VIS));        memset (d, 0, sizeof (d));        for (int i=1; i<=n; ++i) {scanf ("%s", S[i] + 1);} VIS[1] = true;printf ("Case #%d:%s\n", ++cas, (DFS (1)?)    "Yes": "No");} return 0;}

Topological sort/dfs hdoj 4324 Triangle Love