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insert_delete_getrandom_O(1).cpp
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insert_delete_getrandom_O(1).cpp
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//Problem : https://leetcode.com/problems/insert-delete-getrandom-o1/
class RandomizedSet {
public:
/** Initialize your data structure here. */
unordered_set<int> m_set;
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_set.find(val) != m_set.end()){
return false;
}
m_set.insert(val);
return true;
}
/** Removes a value from the set. Returns true if the set contained the specified element. */
bool remove(int val) {
auto it = m_set.find(val);
if(it == m_set.end()){
return false;
}
m_set.erase(it);
return true;
}
/** Get a random element from the set. */
int getRandom() {
int pos = rand()%m_set.size();
auto it = m_set.begin();
for(int i=0;i<pos;i++){
it++;
}
return *it;
}
};
/**
* 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();
*/