Leetcode 380 Solution

https://leetcode.com/problems/insert-delete-getrandom-o1

Solution

``````class RandomizedSet {
unordered_map<int, int> m;
vector<int> v;

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 (m.find(val) != m.end())
return false;

m[val] = v.size();
v.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 (m.find(val) == m.end())
return false;

int i = m[val];
swap(v[i], v.back());
m[v[i]] = i;

m.erase(val);
v.pop_back();

return true;
}

/** Get a random element from the set. */
int getRandom() {
if (v.size() == 0)
return -1;

return v[rand() % v.size()];
}
};

/**
* 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();
*/
``````