Added Is a Graph Bipartite Algorithm

Author: Sanskar-Agrawal01

src/main/java/com/thealgorithms/graph/IsGraphBipartite.java

@@ -0,0 +1,86 @@
+package com.thealgorithms.graph;
+
+import java.util.*;  // For ArrayList, Queue, LinkedList
+
+public class IsGraphBipartite {
+    // Inner class to represent an edge
+    class Edge {
+        int src;
+        int dest;
+
+        public Edge(int s, int d) {
+            this.src = s;
+            this.dest = d;
+        }
+    }
+
+    // Function to check if a graph is bipartite
+    public static boolean isbipartite(ArrayList<Edge>[] graph) {
+        int col[] = new int[graph.length];
+        Arrays.fill(col, -1); // initialize all vertices with -1 (uncolored)
+
+        Queue<Integer> q = new LinkedList<>();
+
+        for (int i = 0; i < graph.length; i++) {
+            if (col[i] == -1) { // unvisited node
+                q.add(i);
+                col[i] = 0; // assign first color
+
+                while (!q.isEmpty()) {
+                    int curr = q.remove();
+                    for (int j = 0; j < graph[curr].size(); j++) {
+                        Edge e = graph[curr].get(j);
+
+                        if (col[e.dest] == -1) {
+                            int nextCol = (col[curr] == 0) ? 1 : 0;
+                            col[e.dest] = nextCol;
+                            q.add(e.dest);
+                        } else if (col[e.dest] == col[curr]) {
+                            return false; // same color conflict
+                        }
+                    }
+                }
+            }
+        }
+        return true;
+    }
+
+    // Converts adjacency list (int[][]) to Edge-based graph and checks bipartiteness
+    public boolean isBipartite(int[][] graph) {
+        ArrayList<Edge>[] graph2 = new ArrayList[graph.length];
+        for (int i = 0; i < graph2.length; i++) {
+            graph2[i] = new ArrayList<>();
+        }
+
+        for (int i = 0; i < graph.length; i++) {
+            for (int j = 0; j < graph[i].length; j++) {
+                int neighbor = graph[i][j];
+                graph2[i].add(new Edge(i, neighbor));
+            }
+        }
+
+        return isbipartite(graph2);
+    }
+
+    // Test the function
+    public static void main(String[] args) {
+        IsGraphBipartite sol = new IsGraphBipartite();
+
+        // Example 1: Bipartite graph
+        int[][] graph1 = {
+            {1, 3},
+            {0, 2},
+            {1, 3},
+            {0, 2}
+        };
+        System.out.println("Graph 1 is bipartite: " + sol.isBipartite(graph1)); // true
+
+        // Example 2: Non-bipartite graph (odd cycle)
+        int[][] graph2 = {
+            {1, 2},
+            {0, 2},
+            {0, 1}
+        };
+        System.out.println("Graph 2 is bipartite: " + sol.isBipartite(graph2)); // false
+    }
+}