solved split wise

src/com/soumya/splitwise/ExpenseManager.java

@@ -0,0 +1,209 @@
+package com.soumya.splitwise;
+
+import java.util.*;
+
+// ExpenseManager : Handles the User Registration and Book keeping tasks. Core functionality of Split Wise. 
+public class ExpenseManager {
+
+	private Map<String, User> users; // Map of registered Users, uid:User
+	private Map<String, Float> expenses; // Map of Expenses "uid_borrower uid_lender":amount
+	private int userCount; // Keeps count of registered users
+
+	// Default Constructor
+	public ExpenseManager() {
+		users = new HashMap<>();
+		expenses = new HashMap<>();
+		userCount = 0;
+	}
+
+	// Register Users
+	public void registerUser(String name, String email, String mob_no) {
+		userCount++;
+		String uid="u"+userCount;
+		users.put(uid, new User(uid,name,email,mob_no));
+	}
+
+	// Display all registered Users
+	public void displayRegisteredUsers() {
+		if(users.size()==0) {
+			System.out.println("No Users Registgered");
+			return;
+		}
+		System.out.println("UID\t\tNAME\t\tEMAIL\t\t\tMOBILE NO.");
+		users.forEach((key, value)->{
+			System.out.println(value.getUid()+"\t\t"+value.getName()+"\t\t"+value.getEmail()+"\t\t"+value.getMob_no());
+		});
+	}
+
+	// Add new or update "uid_borrower uid_lender":amount entry in expenses
+	private void registerExpense(String uid_borrow, String uid_lend, float amt) {
+		// If uid_lend has previous entry of owing money to uid_borrow
+		String key=uid_lend+" "+uid_borrow;
+		if(expenses.containsKey(key)) {
+			expenses.put(key, expenses.get(key)-amt);
+			if(expenses.get(key)==0)
+				expenses.remove(key);
+		}
+		else {
+			// If uid_borrow has previous entry of owing money to uid_lend
+			key=uid_borrow+" "+uid_lend;
+			if(expenses.containsKey(key))
+				expenses.put(key, expenses.get(key)+amt);
+			else // Create entry 
+				expenses.put(key, amt);
+			if(expenses.get(key)==0) // If amount==0 delete expense entry from the map
+				expenses.remove(key);
+		}
+	}
+
+	// Display all expense entries
+	private void showAllBalances() {
+		if(expenses.size()==0) {
+			System.out.println("No balances");
+			return;
+		}
+		expenses.forEach((key, value) -> {
+			String usrs[] = key.split(" ");
+			User user1 = users.get(usrs[0]), user2=users.get(usrs[1]);
+			float val=(float)(Math.round(Math.abs(value) * Math.pow(10, 2)) / Math.pow(10, 2));
+			if(value>0) 
+				System.out.println(user1.getName()+" owes "+user2.getName()+": "+val);
+			else
+				System.out.println(user2.getName()+" owes "+user1.getName()+": "+val);
+		});
+	}
+
+	// Display expense entries for specific user
+	private void showBalanceForUser(String uid) {
+		if(!users.containsKey(uid)) {
+			System.out.println("ERROR: Unknown User !");
+			return;
+		}
+		int flag[]= {0};
+		expenses.forEach((key, value) -> {
+			if(!key.contains(uid))
+				return;
+			flag[0]++;
+			String usrs[] = key.split(" ");
+			User user1 = users.get(usrs[0]), user2=users.get(usrs[1]);
+			if(value>0) 
+				System.out.println(user1.getName()+" owes "+user2.getName()+": "+value);
+			else
+				System.out.println(user2.getName()+" owes "+user1.getName()+": "+Math.abs(value));
+		});
+		if(flag[0]==0)
+			System.out.println("No balances");
+	}
+
+	// Handles EXACT distribution flow 
+	private String exactDistribute(String expense[], String uid, float amt, int share_count, int indx) {
+		float sum=(float) 0.0;
+		for(int i=indx+1;i<=indx+share_count;i++)
+			sum+=Float.parseFloat(expense[i]);
+		if(sum!=amt)
+			return "ERROR: Expenses do not Add Up !";
+		for(int i=1,uindx=3,pindx=indx;i<=share_count;i++)
+			if(!expense[uindx+i].equals(uid))
+				registerExpense(expense[uindx+i],uid,Float.parseFloat(expense[pindx+i]));
+		return "UPDATED";
+
+	}
+
+	// Handles EQUAL distribution flow
+	private String equalDistribute(String expense[], String uid, float amt, int share_count, int indx) {
+		float val=amt/share_count;
+		for(int uindx=4;uindx<4+share_count;uindx++)
+			if(!expense[uindx].equals(uid))
+				registerExpense(expense[uindx],uid,val);
+		return "UPDATED"; 
+	}
+
+	// Handles PERCENT distribution flow
+	private String percentDistribute(String expense[], String uid, float amt, int share_count, int indx) {
+		float sum=(float) 0.0;
+		for(int i=indx+1;i<=indx+share_count;i++)
+			sum+=Float.parseFloat(expense[i]);
+		if(sum!=100.0)
+			return "ERROR: Expenses do not Add Up !";
+		for(int i=1,uindx=3,pindx=indx;i<=share_count;i++) {
+			float val=(float) (amt*1.0*Float.parseFloat(expense[pindx+i])/100);
+			if(!expense[uindx+i].equals(uid))
+				registerExpense(expense[uindx+i],uid,val);
+		}
+		return "UPDATED";
+
+	}
+
+	// Handles SHARE distribution flow
+	private String shareDistribute(String expense[], String uid, float amt, int share_count, int indx) {
+		float sum=(float) 0.0;
+		for(int i=indx+1;i<=indx+share_count;i++)
+			sum+=Float.parseFloat(expense[i]);
+		for(int i=1,uindx=3,pindx=indx;i<=share_count;i++) {
+			float val=(float) (amt*1.0*Float.parseFloat(expense[pindx+i])/sum);
+			if(!expense[uindx+i].equals(uid))
+				registerExpense(expense[uindx+i],uid,val);
+		}
+		return "UPDATED";
+
+	}
+
+	// Driver for the EXPENSE flow, also performs data validation
+	private String computeExpenses(String expense[]) {
+		try {
+			String uid_lend=expense[1];
+			if(!users.containsKey(uid_lend))
+				return "ERROR: Unknown UID- "+uid_lend+" !";
+			float amt = Float.parseFloat(expense[2]);
+			int share_count=Integer.parseInt(expense[3]);
+			int indx=4+share_count;
+			for(int uindx=4;uindx<4+share_count;uindx++)
+				if(!users.containsKey(expense[uindx]))
+					return "ERROR: Unknown UID- "+expense[uindx]+" !";
+			if(expense[indx].equalsIgnoreCase("EQUAL")) {
+				return equalDistribute(expense, uid_lend, amt, share_count, indx);
+			}
+			else if(expense[indx].equalsIgnoreCase("EXACT")) {
+				return exactDistribute(expense, uid_lend, amt, share_count, indx);
+			}
+			else if(expense[indx].equalsIgnoreCase("PERCENT")) {
+				return percentDistribute(expense, uid_lend, amt, share_count, indx);
+			}
+			else if(expense[indx].equalsIgnoreCase("SHARE")) {
+				return shareDistribute(expense, uid_lend, amt, share_count, indx);
+			}
+			else
+				return "ERROR: Unknown Expense Code !";
+		}
+		catch(ArrayIndexOutOfBoundsException e) {
+			return "ERROR: Malformed Input !";
+		}
+
+	}
+
+	// Handler to parse the requests and call appropriate functions  
+	public void handleRequest(String request) {
+
+/*		--DEBUGGING PURPOSE--
+ * 
+ * 		System.out.println("HANDLING REQUEST FOR : "+request);
+ * 		System.out.println(expenses);
+ */
+		String req[]=request.split(" "),resp="";
+		if(req[0].equalsIgnoreCase("EXPENSE")) {
+			if(!(resp=computeExpenses(req)).equals("UPDATED"))
+				System.out.println(resp);
+		}
+		else if(req[0].equalsIgnoreCase("SHOW")) {
+			if(req.length==1)
+				showAllBalances();
+			else if(req.length==2)
+				showBalanceForUser(req[1]);
+			else
+				System.out.println("ERROR: Malformed Input !");
+		}
+		else
+			System.out.println("ERROR: Malformed Input !");
+	}
+
+}

src/com/soumya/splitwise/SplitWiseApp.java

@@ -0,0 +1,38 @@
+package com.soumya.splitwise;
+
+// Driver Application
+public class SplitWiseApp {
+
+	public static void main(String[] args) {
+		// Initializing ExpenseManager Object
+		ExpenseManager expman =  new ExpenseManager();
+
+		// Hard Coded Users
+		expman.registerUser("User1", "user1@hello.com", "+918685483458");
+		expman.registerUser("User2", "user2@hello.com", "+918085483643");
+		expman.registerUser("User3", "user3@hello.com", "+919056783458");
+		expman.registerUser("User4", "user4@hello.com", "+919885434258");
+
+		// Display Registered Users with UID
+		expman.displayRegisteredUsers();
+
+		// TEST - Taken from SAMPLE INPUT Section
+		expman.handleRequest("SHOW");
+		expman.handleRequest("SHOW u1");
+		// EQUAL
+		expman.handleRequest("EXPENSE u1 1000 4 u1 u2 u3 u4 EQUAL");
+		expman.handleRequest("SHOW u4");
+		expman.handleRequest("SHOW u1");
+		// EXACT
+		expman.handleRequest("EXPENSE u1 1250 2 u2 u3 EXACT 370 880");
+		expman.handleRequest("SHOW");
+		// PERCENT
+		expman.handleRequest("EXPENSE u4 1200 4 u1 u2 u3 u4 PERCENT 40 20 20 20");
+		expman.handleRequest("SHOW u1");
+		expman.handleRequest("SHOW");
+		// SHARE
+		expman.handleRequest("EXPENSE u4 1200 4 u1 u2 u3 u4 SHARE 2 1 1 1");
+		expman.handleRequest("SHOW");
+	}
+
+}

src/com/soumya/splitwise/User.java

@@ -0,0 +1,48 @@
+package com.soumya.splitwise;
+
+// Defines the characteristics of a user
+public class User {
+
+	private String name,uid,email,mob_no;
+
+	public User(String uid, String name, String email, String mob_no) {
+		super();
+		this.name = name;
+		this.uid = uid;
+		this.email = email;
+		this.mob_no = mob_no;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public String getUid() {
+		return uid;
+	}
+
+	public void setUid(String uid) {
+		this.uid = uid;
+	}
+
+	public String getEmail() {
+		return email;
+	}
+
+	public void setEmail(String email) {
+		this.email = email;
+	}
+
+	public String getMob_no() {
+		return mob_no;
+	}
+
+	public void setMob_no(String mob_no) {
+		this.mob_no = mob_no;
+	}
+
+}