# Solution

• ``````    ArrayList<Integer> randomList;
Map<Integer, Integer> locMap;
Random random = new Random();

/** Initialize your data structure here. */
public RandomizedSet() {
randomList = new ArrayList<>();
locMap = new HashMap<>();
}

/** Inserts a value to the set. Returns true if the set did not already contain the specified element. */
public boolean insert(int val) {

// check if it's in map
return false;
}

locMap.put(val, randomList.size());
}

/** Removes a value from the set. Returns true if the set contained the specified element. */
public boolean remove(int val) {
boolean exists = locMap.containsKey(val);
if(!exists) {
return false;
}
int location = locMap.get(val);
int listSize = randomList.size() -1;
if(location < listSize) {
// if the value is not the last one in the list,
// swap it with last one and then remove the last
int temp = randomList.get(location);
int last = randomList.get(listSize);
randomList.set(location, last );
//update the map
locMap.put(last, location);
}
randomList.remove(listSize);
locMap.remove(val);
return true;
}

/** Get a random element from the set. */
public int getRandom() {
System.out.println(randomList.size());
return randomList.get(random.nextInt(randomList.size()));
}
}

/**
* Your RandomizedSet object will be instantiated and called as such:
* RandomizedSet obj = new RandomizedSet();
* boolean param_1 = obj.insert(val);
* boolean param_2 = obj.remove(val);
* int param_3 = obj.getRandom();
*/
``````

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