2685_Count_the_Number_of_Complete_Componets.java

Author: vishwajeetmishra4

JAVA/2685_Count_the_Number_of_Complete_Componets.java

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+// Problem Number: 2685
+
+// Count the Number of Complete Components.
+
+class UnionFind {
+  public UnionFind(int n) {
+    id = new int[n];
+    rank = new int[n];
+    nodeCount = new int[n];
+    edgeCount = new int[n];
+    for (int i = 0; i < n; ++i) {
+      id[i] = i;
+      nodeCount[i] = 1;
+    }
+  }
+
+  public void unionByRank(int u, int v) {
+    final int i = find(u);
+    final int j = find(v);
+    ++edgeCount[i];
+    if (i == j)
+      return;
+    if (rank[i] < rank[j]) {
+      id[i] = j;
+      edgeCount[j] += edgeCount[i];
+      nodeCount[j] += nodeCount[i];
+    } else if (rank[i] > rank[j]) {
+      id[j] = i;
+      edgeCount[i] += edgeCount[j];
+      nodeCount[i] += nodeCount[j];
+    } else {
+      id[i] = j;
+      edgeCount[j] += edgeCount[i];
+      nodeCount[j] += nodeCount[i];
+      ++rank[j];
+    }
+  }
+
+  public int find(int u) {
+    return id[u] == u ? u : (id[u] = find(id[u]));
+  }
+
+  public boolean isComplete(int u) {
+    return nodeCount[u] * (nodeCount[u] - 1) / 2 == edgeCount[u];
+  }
+
+  private int[] id;
+  private int[] rank;
+  private int[] nodeCount;
+  private int[] edgeCount;
+}
+
+class Solution {
+  public int countCompleteComponents(int n, int[][] edges) {
+    int ans = 0;
+    UnionFind uf = new UnionFind(n);
+    Set<Integer> parents = new HashSet<>();
+
+    for (int[] edge : edges) {
+      final int u = edge[0];
+      final int v = edge[1];
+      uf.unionByRank(u, v);
+    }
+
+    for (int i = 0; i < n; ++i) {
+      final int parent = uf.find(i);
+      if (parents.add(parent) && uf.isComplete(parent))
+        ++ans;
+    }
+
+    return ans;
+  }
+}