Design a HashMap without using any built-in hash table libraries.
Implement the MyHashMap
class:
-
MyHashMap()
initializes the object with an empty map. -
void put(int key, int value)
inserts a(key, value)
pair into the HashMap. If thekey
already exists in the map, update the correspondingvalue
. -
int get(int key)
returns thevalue
to which the specifiedkey
is mapped, or-1
if this map contains no mapping for thekey
. -
void remove(key)
removes thekey
and its correspondingvalue
if the map contains the mapping for thekey
.
Example 1:
Input
["MyHashMap", "put", "put", "get", "get", "put", "get", "remove", "get"]
[[], [1, 1], [2, 2], [1], [3], [2, 1], [2], [2], [2]]
Output
[null, null, null, 1, -1, null, 1, null, -1]
Explanation
MyHashMap myHashMap = new MyHashMap();
myHashMap.put(1, 1); // The map is now [[1,1]]
myHashMap.put(2, 2); // The map is now [[1,1], [2,2]]
myHashMap.get(1); // return 1, The map is now [[1,1], [2,2]]
myHashMap.get(3); // return -1 (i.e., not found), The map is now [[1,1], [2,2]]
myHashMap.put(2, 1); // The map is now [[1,1], [2,1]] (i.e., update the existing value)
myHashMap.get(2); // return 1, The map is now [[1,1], [2,1]]
myHashMap.remove(2); // remove the mapping for 2, The map is now [[1,1]]
myHashMap.get(2); // return -1 (i.e., not found), The map is now [[1,1]]
Constraints:
-
0 <= key, value <= 106
- At most
104
calls will be made toput
,get
, andremove
.
SOLUTION:
class MyHashMap:
def __init__(self):
self.size = 107
self.arr = [[] for i in range(self.size)]
def hfn(self, key):
key = ((key >> 16) ^ key) * 0x45d9f3b
key = ((key >> 16) ^ key) * 0x45d9f3b
key = (key >> 16) ^ key
return key % self.size
def put(self, key: int, value: int) -> None:
self.remove(key)
self.arr[self.hfn(key)].append((key, value))
def get(self, key: int) -> int:
curr = self.arr[self.hfn(key)]
val = -1
for k, v in curr:
if k == key:
val = v
break
return val
def remove(self, key: int) -> None:
k = len(self.arr[self.hfn(key)])
for i in range(k):
if self.arr[self.hfn(key)][i][0] == key:
self.arr[self.hfn(key)][i] = self.arr[self.hfn(key)][-1]
self.arr[self.hfn(key)].pop()
break
# Your MyHashMap object will be instantiated and called as such:
# obj = MyHashMap()
# obj.put(key,value)
# param_2 = obj.get(key)
# obj.remove(key)
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