feat(graph): add MergeAccounts utility demonstrating email-based merging

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

@@ -0,0 +1,90 @@
+package com.thealgorithms.graph;
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+public class MergeAccounts {
+/**
+ * Merges accounts that share at least one common email address.
+ * 
+ * <p>This method takes a list of accounts, where each account is represented as a list of strings:
+ * the first element is the account holder's name, followed by one or more email addresses.
+ * It merges accounts that share both the same name and at least one email address into a single list,
+ * removing duplicates and redundant entries.</p>
+ *
+ * @param inputList a list of accounts, each represented as [name, email1, email2, ...]
+ */
+
+    private static List<Integer> Unneeded = new ArrayList<Integer>();
+    private static List<List<String>> originalAccounts;
+    public static List<List<String>> mergeAccounts(List<List<String>> inputAccounts){
+        originalAccounts = inputAccounts;
+        for (int account = 0; account < originalAccounts.size(); account++) {
+            for (int otherAccount = account+1; otherAccount < originalAccounts.size(); otherAccount++) {
+                if (account != otherAccount){
+                    if(sameNameCheck(account,otherAccount)&&sameEmailCheck(account,otherAccount)){
+                        overlapItems(account, otherAccount);
+                    }
+
+
+                }
+            }
+
+        }
+    removeUnneeded();
+    return originalAccounts;
+// 
+    }
+
+    public static void removeUnneeded() {
+        Collections.sort(Unneeded);
+        // System.out.println(Unneeded);
+        for (int a = Unneeded.size()-1; a > -1 ; a--) {
+            int i = Unneeded.get(a);
+            // System.out.println(i);
+            originalAccounts.remove(i);
+        }
+    }
+    public static boolean sameNameCheck(int acc1, int acc2) {
+        return(originalAccounts.get(acc1).get(0).equals(originalAccounts.get(acc2).get(0)));
+    }
+
+    public static boolean sameEmailCheck(int acc1, int acc2) {
+        // originalAccounts[acc1] originalAccounts[acc2]
+        // array of 3
+        int acc1Size = originalAccounts.get(acc1).size();
+        int acc2Size = originalAccounts.get(acc2).size();
+        for (int email = 1; email < acc1Size; email++) {
+            for (int otherEmail = 1; otherEmail < acc2Size; otherEmail++) {
+                // System.out.println("Compared "+ originalAccounts[acc1][email]+ " and "+ originalAccounts[acc2][otherEmail]);
+                if (originalAccounts.get(acc1).get(email).equals(originalAccounts.get(acc2).get(otherEmail)))
+                    return true;
+            }
+        }
+        return false;
+
+    }
+    public static void overlapItems(int acc1, int acc2) {
+        int acc1Size = originalAccounts.get(acc1).size();
+        int acc2Size = originalAccounts.get(acc2).size();
+        if (acc1Size < acc2Size){
+            int temp = acc1;
+            acc1 = acc2;
+            acc2= temp;
+            temp = acc1Size;
+            acc1Size = acc2Size;
+            acc2Size = temp;
+        }
+        for (int email = 1; email < acc1Size; email++) {
+            for (int otherEmail = 1; otherEmail < acc2Size; otherEmail++) {
+                if (!originalAccounts.get(acc1).contains(originalAccounts.get(acc2).get(otherEmail)))
+                    originalAccounts.get(acc1).add(originalAccounts.get(acc2).get(otherEmail));
+
+            }
+        }
+                Unneeded.add(acc2);
+
+
+    }
+
+}