O(1) time and o(n) space using Array.

Author: 149ps

706. Design HashMap/706. Design HashMap.py

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+"""
+Design a HashMap without using any built-in hash table libraries.
+
+To be specific, your design should include these functions:
+
+put(key, value) : Insert a (key, value) pair into the HashMap. If the value already exists in the HashMap, update the value.
+get(key): Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key.
+remove(key) : Remove the mapping for the value key if this map contains the mapping for the key.
+
+Example:
+
+MyHashMap hashMap = new MyHashMap();
+hashMap.put(1, 1);
+hashMap.put(2, 2);
+hashMap.get(1);            // returns 1
+hashMap.get(3);            // returns -1 (not found)
+hashMap.put(2, 1);          // update the existing value
+hashMap.get(2);            // returns 1
+hashMap.remove(2);          // remove the mapping for 2
+hashMap.get(2);            // returns -1 (not found)
+
+Note:
+
+All keys and values will be in the range of [0, 1000000].
+The number of operations will be in the range of [1, 10000].
+Please do not use the built-in HashMap library.
+"""
+
+
+class MyHashMap:
+
+    def __init__(self):
+        """
+        Initialize your data structure here.
+        """
+        self.hmap = [-1] * 1000001
+
+    def put(self, key: int, value: int) -> None:
+        """
+        value will always be non-negative.
+        """
+        self.hmap[key] = value
+
+    def get(self, key: int) -> int:
+        """
+        Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key
+        """
+        return self.hmap[key]
+
+    def remove(self, key: int) -> None:
+        """
+        Removes the mapping of the specified value key if this map contains a mapping for the key
+        """
+        self.hmap[key] = -1
+
+# Your MyHashMap object will be instantiated and called as such:
+# obj = MyHashMap()
+# obj.put(key,value)
+# param_2 = obj.get(key)
+# obj.remove(key)