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380.java
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380.java
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__________________________________________________________________________________________________
sample 50 ms submission
class RandomizedSet {
private HashMap<Integer, Integer> map;
private ArrayList<Integer> list;
java.util.Random rand = new java.util.Random();
/** Initialize your data structure here. */
public RandomizedSet() {
map = new HashMap<>();
list = 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(map.containsKey(val)) return false;
else{
map.put(val, list.size());
list.add(val);
}
return true;
}
/** Removes a value from the set. Returns true if the set contained the specified element. */
public boolean remove(int val) {
if(!map.containsKey(val)) return false;
else{
int index = map.get(val);
if(index < list.size() - 1){
int last = list.get(list.size() - 1);
list.set(index,last);
map.put(last,index);
}
map.remove(val);
list.remove(list.size() - 1);
}
return true;
}
/** Get a random element from the set. */
public int getRandom() {
return list.get(rand.nextInt(list.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();
*/
__________________________________________________________________________________________________
sample 40276 kb submission
class RandomizedSet {
Map<Integer, Integer> map;
List<Integer> list;
/** Initialize your data structure here. */
public RandomizedSet() {
map = new HashMap<>();
list = 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) {
boolean isPresent = map.containsKey(val);
if(!isPresent) {
list.add(val);
map.put(val, list.size()-1);
}
return !isPresent;
}
/** Removes a value from the set. Returns true if the set contained the specified element. */
public boolean remove(int val) {
boolean isPresent = map.containsKey(val);
if(isPresent) {
int index = map.get(val);
if(index == list.size()-1) {
list.remove(index);
}else {
// get the value of swapped item so that we can update its index in the map
// so that later on if this item gets deleted , index will be correct.
int swapItem = list.get(list.size()-1);
Collections.swap(list, index, list.size()-1);
list.remove(list.size()-1);
map.put(swapItem, index);
}
map.remove(val);
}
return isPresent;
}
/** Get a random element from the set. */
public int getRandom() {
int max = list.size();
int min = 0;
int ind = (int)(Math.random() * (max - min) + min);
return list.get(ind);
}
}
/**
* 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();
*/
__________________________________________________________________________________________________