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getrandom.js
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getrandom.js
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/**
* Initialize your data structure here.
*/
const swap = (arr, indexA, indexB) => {
const temp = arr[indexA];
arr[indexA] = arr[indexB];
arr[indexB] = temp;
};
const RandomizedSet = function () {
this.map = {};
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) {
const index = this.map[val];
if (index !== undefined) {
return false;
}
this.arr.push(val);
this.map[val] = this.arr.length - 1;
return true;
};
/**
* 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) {
const index = this.map[val];
if (index !== undefined) {
if (index !== this.arr.length - 1) {
this.map[this.arr[this.arr.length - 1]] = index;
swap(this.arr, index, this.arr.length - 1);
}
delete this.map[val];
this.arr.pop();
return true;
}
return false;
};
/**
* Get a random element from the set.
* @return {number}
*/
RandomizedSet.prototype.getRandom = function () {
const randomIndex = Math.floor(Math.random() * this.arr.length);
return this.arr[randomIndex];
};
/**
* Your RandomizedSet object will be instantiated and called as such:
* var obj = Object.create(RandomizedSet).createNew()
* var param_1 = obj.insert(val)
* var param_2 = obj.remove(val)
* var param_3 = obj.getRandom()
*/