Merge pull request #773 from coderanant/master

feat: add algo to find no of connected components with Union Find Structure

graph/connected_components_with_dsu.cpp

@@ -0,0 +1,55 @@
+#include <iostream>
+#include <vector>
+#include <set>
+
+int N;  // denotes number of nodes;
+std::vector<int> parent;
+std::vector<int> siz;
+void make_set() {  // function the initialize every node as it's own parent
+    for (int i = 1; i <= N; i++) {
+        parent[i] = i;
+        siz[i] = 1;
+    }
+}
+// To find the component where following node belongs to
+int find_set(int v) {
+    if (v == parent[v])
+        return v;
+    return parent[v] = find_set(parent[v]);
+}
+
+void union_sets(int a, int b) {  // To join 2 components to belong to one
+    a = find_set(a);
+    b = find_set(b);
+    if (a != b) {
+        if (siz[a] < siz[b])
+            std::swap(a, b);
+        parent[b] = a;
+        siz[a] += siz[b];
+    }
+}
+
+int no_of_connected_components() {  // To find total no of connected components
+    std::set<int> temp;  // temp set to count number of connected components
+    for (int i = 1; i <= N; i++)
+        temp.insert(find_set(i));
+    return temp.size();
+}
+
+// All critical/corner cases have been taken care of.
+// Input your required values: (not hardcoded)
+int main() {
+    std::cin >> N;
+    parent.resize(N + 1);
+    siz.resize(N + 1);
+    make_set();
+    int edges;
+    std::cin >> edges;  // no of edges in the graph
+    while (edges--) {
+        int node_a, node_b;
+        std::cin >> node_a >> node_b;
+        union_sets(node_a, node_b);
+    }
+    std::cout << no_of_connected_components() << std::endl;
+    return 0;
+}