LeetCode—380. Insert Delete GetRandom O(1)s

Insert Delete GetRandom O(1)
思路：java中的list提供了针对制定元素删除的方法以及判断该元素是否存在的方法

GitHub地址：https://github.com/corpsepiges/leetcode

目前java版本的答案大约进度是免费的差40题，python大约是一半，其他的等以后再补充。

点此进入如果可以的话，请点一下star，谢谢。

import java.util.Random;
public class RandomizedSet {
List<Integer> list;
Random r;
/** Initialize your data structure here. */
public RandomizedSet() {
list=new ArrayList<Integer>();
r=new Random();
}

/** Inserts a value to the set. Returns true if the set did not already contain the specified element. */
public boolean insert(int val) {
Integer v=val;
if(list.contains(v)){
return false;
}
list.add(v);
return true;
}

/** Removes a value from the set. Returns true if the set contained the specified element. */
public boolean remove(int val) {
Integer v=val;
if(list.contains(v)){
list.remove(v);
return true;
}
return false;
}

/** Get a random element from the set. */
public int getRandom() {
return list.get(r.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();
*/