/**
* Initialize your data structure here.
*/varRandomizedSet=function(){this.hashTable ={};this.arr =[];};/**
* Inserts a value to the set. Returns true if the set did not already contain the specified element.
* @param {number} val
* @return {boolean}
*/RandomizedSet.prototype.insert=function(val){if(this.hashTable[val]!==undefined)returnfalse;this.hashTable[val]=this.arr.length;this.arr.push(val);returntrue;};/**
* Removes a value from the set. Returns true if the set contained the specified element.
* @param {number} val
* @return {boolean}
*/RandomizedSet.prototype.remove=function(val){if(this.hashTable[val]===undefined)returnfalse;var index =this.hashTable[val];var key =this.arr[this.arr.length-1];this.hashTable[key]= index;deletethis.hashTable[val];this.arr[index]= key;this.arr.pop();returntrue;};/**
* Get a random element from the set.
* @return {number}
*/RandomizedSet.prototype.getRandom=function(){returnthis.arr[~~(Math.random()*this.arr.length)];};/**
* Your RandomizedSet object will be instantiated and called as such:
* var obj = new RandomizedSet()
* var param_1 = obj.insert(val)
* var param_2 = obj.remove(val)
* var param_3 = obj.getRandom()
*/