Discuss the implementation of hash tables with open addressing in different programming languages.

Hash tables with open addressing are a popular data structure used for efficient storage and retrieval of key-value pairs. In this implementation, collisions are resolved by finding an alternative empty slot within the hash table to store the collided element. Let's discuss the implementation of hash tables with open addressing in different programming languages.

1. Python:
Python provides a built-in data structure called "dict" which is implemented using hash tables. The open addressing technique is used to handle collisions. Python's dict uses a technique called "probing" to find an empty slot when a collision occurs. Probing involves searching for the next available slot in the hash table until an empty slot is found. Python's dict also dynamically resizes the hash table to maintain a load factor below a certain threshold.

2. Java:
Java provides a class called "HashMap" which is implemented using hash tables with open addressing. Java's HashMap uses an array of "Entry" objects to store key-value pairs. When a collision occurs, Java's HashMap uses linear probing to find the next available slot. If linear probing fails, it uses a technique called "double hashing" to find an alternative slot. Double hashing involves using a second hash function to calculate the step size for probing.

3. C++:
C++ does not provide a built-in hash table implementation, but it offers the "unordered_map" class from the Standard Template Library (STL). The unordered_map class is implemented using hash tables with open addressing. C++'s unordered_map uses linear probing to handle collisions. When a collision occurs, it searches for the next available slot by incrementing the index until an empty slot is found.

4. JavaScript:
JavaScript provides a built-in data structure called "Map" which is implemented using hash tables with open addressing. JavaScript's Map uses a technique called "chaining" to handle collisions. Chaining involves storing collided elements in linked lists attached to each slot of the hash table. When a collision occurs, JavaScript's Map appends the collided element to the linked list associated with the slot.

5. Ruby:
Ruby provides a built-in class called "Hash" which is implemented using hash tables with open addressing. Ruby's Hash uses a technique called "rehashing" to handle collisions. Rehashing involves finding an alternative slot by applying a secondary hash function to the key. If the secondary hash function fails to find an empty slot, Ruby's Hash uses linear probing to search for the next available slot.

In conclusion, hash tables with open addressing are implemented differently in various programming languages. Each language provides its own data structure or class that utilizes different collision resolution techniques such as probing, double hashing, chaining, or rehashing. These implementations ensure efficient storage and retrieval of key-value pairs in hash tables.