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package test1;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.Random;

public class RandomSet {

HashMap<Integer, Integer> randomObj;

HashMap<Integer, Integer> objIndexes;

ArrayList<Integer> keyList;

/** Initialize your data structure here. */

public RandomSet() {

randomObj = new HashMap<>();

objIndexes = new HashMap<>();

keyList = new ArrayList<>();

}

/** Inserts a value to the set. Returns true if the set did not already contain the specified element. */

public boolean insert(int val) {

if (randomObj.containsKey(val))

return false;

else {

randomObj.put(val, val);

keyList.add(val);

objIndexes.put(val, keyList.size()-1);

System.out.println("List size after insert: "+keyList.size());

System.out.println("List after insert: "+keyList.toString());

return true;

}

}

/** Removes a value from the set. Returns true if the set contained the specified element. */

public boolean remove(int val) {

if (! randomObj.containsKey(val))

return false;

else {

randomObj.remove(val);

int ind = objIndexes.get(val);

int last = keyList.size()-1;

if (ind==last) {

keyList.remove(ind);

} else {

keyList.add(ind, keyList.get(last));

keyList.remove(last);

}

System.out.println("List size after remove: "+keyList.size());

System.out.println("List after remove: "+keyList.toString());

objIndexes.remove(val);

return true;

}

}

/** Get a random element from the set. */

public int getRandom() {

Random r = new Random();

int rand = r.nextInt(keyList.size());

//System.out.println("keyList.size()=="+keyList.size());

//System.out.println("rand=="+rand);

return randomObj.get(keyList.get(r.nextInt(keyList.size())));

}

public static void main(String[] args) {

RandomSet s = new RandomSet();

s.insert(0);

s.insert(1);

s.remove(0);

s.insert(2);

s.remove(1);

//s.getRandom();

}

}