number of connected components in an undirected graph solution

Author: Tessa1217

number-of-connected-components-in-an-undirected-graph/Tessa1217.java

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+import java.util.*;
+
+public class Solution {
+
+    // Union Find
+    public int countComponents(int n, int[][] edges) {
+
+        List<Integer> parent = clearGraph(n);
+
+        for (int[] edge : edges) {
+            union(parent, edge[0], edge[1]);
+        }
+
+        Set<Integer> componentRoots = new HashSet<>();
+        for (int i = 0; i < n; i++) {
+            componentRoots.add(find(parent, i));
+        }
+
+        return componentRoots.size();
+    }
+
+    private void union(List<Integer> parent, int x, int y) {
+        int px = find(parent, x);
+        int py = find(parent, y);
+        if (px > py) {
+            parent.set(py, px);
+        } else {
+            parent.set(px, py);
+        }
+    }
+
+    private int find(List<Integer> parent, int x) {
+        if (parent.get(x) == x) {
+            return x;
+        }
+        parent.set(x, find(parent, parent.get(x)));
+        return parent.get(x);
+    }
+
+    private List<Integer> clearGraph(int n) {
+        List<Integer> parent = new ArrayList<>();
+        for (int i = 0; i < n; i++) {
+            parent.add(i);
+        }
+        return parent;
+    }
+}
+
+