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-rw-r--r--Sources/GraphAlgo.cpp46
1 files changed, 31 insertions, 15 deletions
diff --git a/Sources/GraphAlgo.cpp b/Sources/GraphAlgo.cpp
index a950767..3fdd795 100644
--- a/Sources/GraphAlgo.cpp
+++ b/Sources/GraphAlgo.cpp
@@ -5,34 +5,51 @@
#include <algorithm>
using std::vector;
-using std::pair;
+//using std::pair;
-void explore(vector<vector<int>> &adj, vector<int> &visited, int v) {
+void explore(vector<vector<int>> &adj, int v, vector<int> &visited, vector<int> &prev,
+ vector<int> &postv, vector<int> &clock) {
visited.push_back(v);
+ prev[v] = clock[0];
+ clock[0] = clock[0] + 1;
for (size_t i = 0; i < adj[v].size(); i++) {
if (std::find(visited.begin(), visited.end(), adj[v][i])
== visited.end())
- explore(adj, visited, adj[v][i]);
+ explore(adj, adj[v][i], visited, prev, postv, clock);
}
+ postv[v] = clock[0];
+ clock[0] = clock[0] + 1;
+
}
-int number_of_components(vector<vector<int> > &adj) {
+void dfs(vector<vector<int>> &adj, vector<int> &visited, vector<int> &prev,
+ vector<int> &postv, vector<int> &clock) {
+ for (size_t v = 0; v < adj.size(); v++) {
+ if (std::find(visited.begin(), visited.end(), v) == visited.end())
+ explore(adj, v, visited, prev, postv, clock);
+ }
+}
+int acyclic(vector<vector<int> > &adj) {
vector<int> visited;
- int cc = 0;
- for (size_t v = 0; v < adj.size(); v++) {
- if (std::find(visited.begin(), visited.end(), v) == visited.end()) {
- explore(adj, visited, v);
- cc++;
+ vector<int> prev(adj.size(), 0);
+ vector<int> postv(adj.size(), 0);
+ vector<int> clock(1, 0);
+ dfs(adj, visited, prev, postv, clock);
+
+ for (size_t u = 0; u < adj.size(); u++) {
+ for (size_t i = 0; i < adj[u].size(); i++) {
+ if (postv[u] <= postv[adj[u][i]])
+ return 1;
}
}
- return cc;
+ return 0;
}
-//TEST(ConnectedComponents, cc1) {
-// vector<vector<int>> adj = { { 1 }, {0, 2 }, { 1 }, { } };
-// ASSERT_EQ(number_of_components(adj), 2);
+//TEST(Acyclicity, ac1) {
+// vector<vector<int>> adj = { { 1 }, { 2 }, { 0 }, { 0 } };
+// ASSERT_EQ(acyclic(adj), 1);
//}
int main() {
@@ -43,7 +60,6 @@ int main() {
int x, y;
std::cin >> x >> y;
adj[x - 1].push_back(y - 1);
- adj[y - 1].push_back(x - 1);
}
- std::cout << number_of_components(adj);
+ std::cout << acyclic(adj);
}