# (LeetCode) 380. Insert Delete GetRandom O(1)

## 380. Insert Delete GetRandom O(1)

• Explore : Interview > Top Interveiw Questions > Medium Collection
• 분류 : Design
• 난이도 : Medium

### Problem

Implement the RandomizedSet class:

• RandomizedSet() Initializes the RandomizedSet object.
• bool insert(int val) Inserts an item val into the set if not present. Returns true if the item was not present, false otherwise.
• bool remove(int val) Removes an item val from the set if present. Returns true if the item was present, false otherwise.
• int getRandom() Returns a random element from the current set of elements (it’s guaranteed that at least one element exists when this method is called). Each element must have the same probability of being returned.

You must implement the functions of the class such that each function works in average O(1) time complexity.

#### Constraints

• -2^31 <= val <= 2^31 - 1
• At most 2 * 10^5 calls will be made to insert, remove, and getRandom.
• There will be at least one element in the data structure when getRandom is called.

### Solution

Exapnder

#### Point of Thinking

• Set의 성질을 그대로 이용한다.
• getRandom() 메서드의 경우 set의 크기만큼 바운드값을 설정한다.
• 대응하는 인터페이스대로 처리하면 Accepted.