Add bipartite graph algo using DFS

desktop.ini

@@ -0,0 +1,2 @@
+[.ShellClassInfo]
+LocalizedResourceName=@Java,0

pom.xml

@@ -7,13 +7,20 @@
     <artifactId>Java</artifactId>
     <version>1.0-SNAPSHOT</version>
     <packaging>jar</packaging>
+    <dependency>
+    <groupId>org.json</groupId>
+    <artifactId>json</artifactId>
+    <version>20240303</version>
+</dependency>
+
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <maven.compiler.source>21</maven.compiler.source>
         <maven.compiler.target>21</maven.compiler.target>
         <assertj.version>3.27.6</assertj.version>
     </properties>
+
 
     <dependencyManagement>
         <dependencies>

src/main/java/com/thealgorithms/conversions/USDtoIND.java

@@ -0,0 +1,89 @@
+package com.thealgorithms.conversions;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.util.Scanner;
+
+public class USDtoIND {
+
+    // ✅ Free, keyless API endpoint
+    private static final String API_URL = "https://open.er-api.com/v6/latest/USD";
+
+    /**
+     * Fetches the live USD to INR rate from open.er-api.com
+     * 
+     * @return the exchange rate, or -1 if an error occurs
+     */
+    public static double fetchLiveRate() {
+        try {
+            // Step 1: Connect to the URL
+            URL url = new URL(API_URL);
+            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
+            conn.setRequestMethod("GET");
+
+            // Step 2: Read API response
+            BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
+            StringBuilder response = new StringBuilder();
+            String line;
+            while ((line = reader.readLine()) != null) {
+                response.append(line);
+            }
+            reader.close();
+
+            // Step 3: Extract INR value manually from the JSON text
+            String json = response.toString();
+
+            // Find INR rate
+            int start = json.indexOf("\"INR\":") + 6;
+            int end = json.indexOf(",", start);
+            if (end == -1)
+                end = json.indexOf("}", start);
+            String rateStr = json.substring(start, end);
+
+            return Double.parseDouble(rateStr);
+        } catch (Exception e) {
+            System.out.println("Error fetching exchange rate: " + e.getMessage());
+            return -1;
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        System.out.println("USD ↔ INR Converter");
+        System.out.println("--------------------");
+        System.out.println("Choose conversion type:");
+        System.out.println("1. USD → INR");
+        System.out.println("2. INR → USD");
+        System.out.print("Enter your choice (1 or 2): ");
+        int choice = sc.nextInt();
+
+        // Fetch live exchange rate
+        double rate = fetchLiveRate();
+
+        if (rate <= 0) {
+            System.out.println("Failed to retrieve live exchange rate. Please check your internet connection.");
+            sc.close();
+            return;
+        }
+
+        // Conversion logic
+        if (choice == 1) {
+            System.out.print("Enter amount in USD: ");
+            double usd = sc.nextDouble();
+            double inr = usd * rate;
+            System.out.printf("%.2f USD = %.2f INR (Rate: %.2f)%n", usd, inr, rate);
+        } else if (choice == 2) {
+            System.out.print("Enter amount in INR: ");
+            double inr = sc.nextDouble();
+            double usd = inr / rate;
+            System.out.printf("%.2f INR = %.2f USD (Rate: %.2f)%n", inr, usd, rate);
+        } else {
+            System.out.println("Invalid choice. Please run the program again and select 1 or 2.");
+        }
+
+        sc.close();
+    }
+}

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

@@ -0,0 +1,132 @@
+package com.thealgorithms.graph;
+
+import java.util.Arrays;
+import java.util.Scanner;
+
+/**
+ * This class provides an implementation to check whether a given graph is
+ * bipartite using Depth First Search (DFS).
+ * 
+ * A bipartite graph is one in which the set of vertices can be divided into two
+ * disjoint subsets
+ * such that no two vertices within the same subset are adjacent.
+ * 
+ * For more information, see
+ * <a href="https://en.wikipedia.org/wiki/Bipartite_graph">Wikipedia: Bipartite
+ * Graph</a>.
+ * 
+ * <p>
+ * Example:
+ * </p>
+ * 
+ * <pre>
+ * Input:
+ * 4 4
+ * 0 1
+ * 1 2
+ * 2 3
+ * 3 0
+ * 
+ * Output:
+ * Graph is Bipartite: true
+ * </pre>
+ * 
+ * Author: Ilma Akram Ansari
+ */
+public final class BipartiteGraphDFS {
+
+    // Private constructor to prevent instantiation
+    private BipartiteGraphDFS() {
+    }
+
+    /**
+     * Checks whether the given undirected graph is bipartite using Depth First
+     * Search (DFS).
+     *
+     * @param graph The adjacency list representation of the graph,
+     *              where graph[i] contains an array of all vertices adjacent to
+     *              vertex i.
+     * @return {@code true} if the graph is bipartite, otherwise {@code false}.
+     */
+    public static boolean isBipartite(int[][] graph) {
+        int n = graph.length;
+        int[] color = new int[n];
+        Arrays.fill(color, -1); // -1 = uncolored
+
+        // Handle disconnected graphs
+        for (int i = 0; i < n; i++) {
+            if (color[i] == -1) {
+                if (!dfs(graph, i, 0, color)) {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Recursive DFS helper method to assign colors and check bipartiteness.
+     *
+     * @param graph     The adjacency list of the graph.
+     * @param node      The current vertex being explored.
+     * @param currColor The color to assign to this vertex (0 or 1).
+     * @param color     Array storing colors of all vertices.
+     * @return {@code true} if no conflict is found, otherwise {@code false}.
+     */
+    private static boolean dfs(int[][] graph, int node, int currColor, int[] color) {
+        color[node] = currColor;
+
+        for (int neighbor : graph[node]) {
+            if (color[neighbor] == -1) {
+                // Assign opposite color to neighbor
+                if (!dfs(graph, neighbor, 1 - currColor, color)) {
+                    return false;
+                }
+            } else if (color[neighbor] == currColor) {
+                // Found same color on adjacent nodes -> not bipartite
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Main method to take input and check if the graph is bipartite.
+     * Input format:
+     * n m
+     * u1 v1
+     * u2 v2
+     * ...
+     * um vm
+     */
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        System.out.println("Enter number of vertices and edges:");
+        int n = sc.nextInt(); // number of vertices
+        int m = sc.nextInt(); // number of edges
+
+        // Using adjacency list representation
+        int[][] temp = new int[n][n]; // temporary adjacency matrix for building adjacency list
+        int[] degree = new int[n]; // degree of each vertex
+
+        System.out.println("Enter each edge (u v):");
+        for (int i = 0; i < m; i++) {
+            int u = sc.nextInt();
+            int v = sc.nextInt();
+            temp[u][degree[u]++] = v;
+            temp[v][degree[v]++] = u; // since graph is undirected
+        }
+
+        // Convert to adjacency list (trim extra zeros)
+        int[][] graph = new int[n][];
+        for (int i = 0; i < n; i++) {
+            graph[i] = Arrays.copyOf(temp[i], degree[i]);
+        }
+
+        boolean result = isBipartite(graph);
+        System.out.println("Graph is Bipartite: " + result);
+
+        sc.close();
+    }
+}