Easy
Design HashMap — C++
Full explanation · Time O(1) · Space O(n)
// Time: O(1)
// Space: O(n)
class MyHashMap {
public:
/** Initialize your data structure here. */
MyHashMap() : data_(10000) {
}
/** value will always be positive. */
void put(int key, int value) {
auto& list = data_[key % data_.size()];
auto it = find_if(list.begin(), list.end(),
[&](const pair<int, int>& i) { return i.first == key; } );
if (it != list.end()) {
it->second = value;
} else {
list.emplace_back(key, value);
}
}
/** Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key */
int get(int key) {
auto& list = data_[key % data_.size()];
auto it = find_if(list.begin(), list.end(),
[&](const pair<int, int>& i) { return i.first == key; } );
if (it != list.end()) {
return it->second;
} else {
return -1;
}
}
/** Removes the mapping of the specified value key if this map contains a mapping for the key */
void remove(int key) {
auto& list = data_[key % data_.size()];
auto it = find_if(list.begin(), list.end(),
[&](const pair<int, int>& i) { return i.first == key; } );
if (it != list.end()) {
list.erase(it);
}
}
private:
vector<list<pair<int, int>>> data_;
};
/**
* Your MyHashMap object will be instantiated and called as such:
* MyHashMap obj = new MyHashMap();
* obj.put(key,value);
* int param_2 = obj.get(key);
* obj.remove(key);
*/