Fix articulations and bridges

Signed-off-by: Bruno Freitas Tissei <bft15@inf.ufpr.br>

graph/articulations_bridges.cpp

 /**
- * Articulations and Bridges
+ * Articulations and Bridges (Tarjan)
  *
  * Complexity (Time): O(n + m)
  * Complexity (Space): O(n + m)
@@ -9,8 +9,10 @@ vector<int> graph[MAX];
 
 int cont[MAX], parent[MAX];
 int low[MAX], L[MAX];
+vector<ii> bridges;
+vector<int> articulations;
 
-// Find all articulations and bridges in the graph
+// Finds all articulations and bridges in the graph
 void dfs(int x) {
   int child = 0;
   cont[x] = 1;
@@ -25,11 +27,10 @@ void dfs(int x) {
       low[x] = min(low[x], low[i]);
 
       if ((parent[x] == -1 && child > 1) || (parent[x] != -1 && low[i] >= L[x]))
-        // CAUTION: may be executed more than once for the same vertex
-        // ==== x is an articulation point ====
+        articulations.pb(x);
 
       if (low[i] > L[x])
-        // ==== (x,i) is a bridge ====
+        bridges.pb(ii(x, i));
 
     } else if (parent[x] != i) {
       low[x] = min(low[x], L[i]);
@@ -41,4 +42,8 @@ void dfs(int x) {
 void tarjan(int v) {
   memset(parent, -1, sizeof parent);
   dfs(v);
+
+  // Remove duplicates for articulations
+  sort(all(articulations));
+  articulations.erase(unique(all(articulations)), articulations.end());
 }