leetcode380

class RandomizedSet {
public:
    /** Initialize your data structure here. */
    RandomizedSet() {

    }

    /** Inserts a value to the set. Returns true if the set did not already contain the specified element. */
    bool insert(int val) {
        if(hash.count(val)) return false;
        hash[val] = vec.size();
        vec.push_back(val);
        return true;
    }

    /** Removes a value from the set. Returns true if the set contained the specified element. */
    bool remove(int val) {
        if(hash.count(val)==) return false;
        int pos = hash[val];
        hash[vec.back()] = pos;
        swap(vec[pos], vec[vec.size()-]);
        hash.erase(val);
        vec.pop_back();
        return true;

    }

    /** Get a random element from the set. */
    int getRandom() {
        return vec[rand()%vec.size()];
    }

private:
    unordered_map<int, int> hash;
    vector<int> vec;
};

/**
 * Your RandomizedSet object will be instantiated and called as such:
 * RandomizedSet obj = new RandomizedSet();
 * bool param_1 = obj.insert(val);
 * bool param_2 = obj.remove(val);
 * int param_3 = obj.getRandom();
 */

数据结构设计问题，从网上找的参考答案。

根据以上的思路，写了一份python版本的代码：

 class RandomizedSet:
     def __init__(self):
         """
         Initialize your data structure here.
         """
         self.dic = dict()
         self.l = list()
         self.length = 

     def insert(self, val: int) -> bool:
         """
         Inserts a value to the set. Returns true if the set did not already contain the specified element.
         """
         if val in self.dic:
             return False
         else:
             self.dic[val] = self.length
             self.l.append(val)
             self.length +=
             return True

     def remove(self, val: int) -> bool:
         """
         Removes a value from the set. Returns true if the set contained the specified element.
         """
         if val not in self.dic:
             return False
         else:
             self.dic.pop(val)
             self.l.remove(val)
             self.length -=
             return True

     def getRandom(self) -> int:
         """
         Get a random element from the set.
         """
         rnd = int(random.uniform(, self.length))
         key = self.l[rnd]
         return key