package algs34;

import java.util.*;

import stdlib.*;

/*

* Complete the methods of MyFriend so that it works.

* Each method must work in the worst case time given below (assuming uniform hashing and ignoring string lengths):

*

* addPerson must take constant time

*

* addFriendship must take constant time

*

* queryFriendship must take constant time

*

* removeFriendship should take constant time

*

* lookupFriends should take time proportional to the number of

* friends that the named person has (or less)

*

* Your solution should use a single field of type

*

* HashMap>

*

* You will need to add hashCode and equals methods to the Person class.

* To increase the avalance effect, consider a hash function that utilizes

* primes, for example:

*

* public int hashCode() {

* int result = 17;

* result = 37*result + var1;

* result = 37*result + var2;

* result = 37*result + var3;

* return result;

* }

*

* Don't change the first line of any method given below.

* The names and types of the methods should not change.

* I will run you MyFriend class using my own main method.

*

* You can add more classes too. Just put them all in this file, inside MyFriend.

* Any classes you add should be "static" and not "public".

* You can import/use any file in the java APIs.

* You can import/use any file in the algs packages.

*

* You do not need to implement a hash table for this assignment.

* You can use java.util.HashMap, java.util.HashSet, or the implementations in algs34.

*

* You do not need to implement an iterable object.

* You can use algs13.Queue.

* Also note that all of the Map implementations we have looked at create an iterable

* object via the keys() method.

*

*

* Here is an example session:

*

* INPUT OUTPUT

*

* p john 8

* p mike 7

* p sara 9

* p jane 5

* f mike 7 jane 5

* f mike 7 sara 9

* f jane 5 john 8

* l jane 5 mike 7 john 8

* l john 8 jane 5

* u mike 7 jane 5

* l jane 5 john 8

* q mike 7 sara 9 yes

* q sara 9 mike 7 yes

* q sara 9 mike 23 no

* q sara 9 sara 9 no

*

* Note that friendship is symmetric and irreflexive.

* So if a/b are friends, then so are b/a.

* And no one is their own friend.

*

* Put the following in a file "input.txt" to run this test:

p john 8

p mike 7

p sara 9

p jane 5

f mike 7 jane 5

f mike 7 sara 9

f jane 5 john 8

l jane 5

l john 8

u mike 7 jane 5

l jane 5

q mike 7 sara 9

q sara 9 mike 7

q sara 9 mike 23

q sara 9 sara 9

*/

public class MyFriend {

public static boolean DEBUG = true;

public static Person makePerson (In in) {

try {

String name = in.readString ();

int age = in.readInt ();

return makePerson (name, age);

} catch (java.util.InputMismatchException e) {

StdOut.println ("Input format error");

return null;

}

}

public static Person makePerson (String name, int age) {

return new Person (name, age);

}

static class Person {

String name;

int age;

public Person (String name, int age) {

this.name = name;

this.age = age;

}

public String toString () {

return name + " " + age;

}

@Override

public boolean equals (Object obj) {

// TODO

return true;

}

@Override

public int hashCode () {

// TODO

return 1293879128; //dummy hascode you have to implement the hashcode

}

}

HashMap> map = new HashMap<>();

// a person "exists" after they are added using addPerson

// addPerson does nothing if p already exists

public void addPerson (Person p) {

// TODO

if (DEBUG) { StdOut.format ("P %s: %s ", p, map); }

}

// addFriendship does nothing if p1 and p2 are already friends or if one does not exist

public void addFriendship (Person p1, Person p2) {

// TODO

if (DEBUG) { StdOut.format ("F %s %s: %s ", p1, p2, map); }

}

// removeFriendship does nothing if p1 and p2 are not friends or if one does not exist

public void removeFriendship (Person p1, Person p2) {

// TODO

if (DEBUG) { StdOut.format ("U %s %s: %s ", p1, p2, map); }

}

// queryFriendship returns false if p1 and p2 are not friends or if one does not exist

public boolean queryFriendship (Person p1, Person p2) {

if (DEBUG) { StdOut.format ("Q %s %s: ", p1, p2); }

// TODO

return false;

}

// lookupFriends returns null or empty iterable if p does not exists

public Iterable lookupFriends (Person p) {

if (DEBUG) { StdOut.format ("L %s:", p); }

// TODO

return null;

}

public static void hashTest () {

Trace.showBuiltInObjects (true);

//Trace.run ();

Person x = makePerson ("bob", 27);

Person y = makePerson ("bob", 27);

Boolean eq = x.equals(y);

Boolean hash = x.hashCode() == y.hashCode();

StdOut.println(x.toString() + " ("+x.hashCode()+") == " + y.toString() + " ("+y.hashCode()+")");

StdOut.println( " Equal Test: " + (eq ? "equal" : "not equal") );

StdOut.println( " Hash Test: " + (hash ? "equal" : "not equal") );

x = makePerson ("mike", 27);

y = makePerson ("john", 29);

eq = x.equals(y);

hash = x.hashCode() == y.hashCode();

StdOut.println(x.toString() + " ("+x.hashCode()+") == " + y.toString() + " ("+y.hashCode()+")");

StdOut.println( " Equal Test: " + (eq ? "equal" : "not equal") );

StdOut.println( " Hash Test: " + (hash ? "equal" : "not equal") );

}

public static void main (String[] args) {

Trace.showBuiltInObjects (true);

//Trace.run ();

hashTest();

/*

* The first line below causes "in" to read from the console. You can

* change this to read from a file, by using something like the line

* below, where "input.txt" is a file you create in your eclipse

* workspace. The file should be in the same folder that contains "src"

* "bin" and "lib":

*/

//In[] inputFiles = new In[] { new In () }; // from console

In[] inputFiles = new In[] { new In ("input.txt") }; // from file

//In[] inputFiles = new In[] { new In ("input.txt"), new In () }; // from file, then console

MyFriend fb = new MyFriend ();

StdOut.println (" ");

StdOut.println ("Enter one of the following:");

StdOut.println (" P name age -- add person");

StdOut.println (" F name1 age1 name2 age2 -- add friendship");

StdOut.println (" U name1 age1 name2 age2 -- remove friendship");

StdOut.println (" Q name1 age1 name2 age2 -- query friendship");

StdOut.println (" L name age -- lookup friends");

StdOut.println (" R -- restart");

StdOut.println (" X -- exit ");

for (In in : inputFiles) {

while (in.hasNextLine ()) {

String action;

try {

action = in.readString ();

} catch (NoSuchElementException e) { continue; }

//StdOut.println (action); // while debugging, print debugging info here! You can print maps, sets, lists.

switch (action) {

case "P":

case "p": {

Person p = makePerson (in);

fb.addPerson (p);

break;

}

case "F":

case "f": {

Person p1 = makePerson (in);

Person p2 = makePerson (in);

fb.addFriendship (p1, p2);

break;

}

case "U":

case "u": {

Person p1 = makePerson (in);

Person p2 = makePerson (in);

fb.removeFriendship (p1, p2);

//Trace.draw ();

break;

}

case "Q":

case "q": {

Person p1 = makePerson (in);

Person p2 = makePerson (in);

boolean result = fb.queryFriendship (p1, p2);

StdOut.println (result ? "Yes" : "No");

break;

}

case "L":

case "l": {

Person p = makePerson (in);

Iterable result = fb.lookupFriends (p);

if (result != null) {

for (Person friend : result) {

StdOut.print (friend);

StdOut.print (" ");

}

}

StdOut.println ();

break;

}

case "R":

case "r":

fb = new MyFriend ();

break;

case "X":

case "x":

System.exit (0);

}

}

}

}

}