{ }

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Optimizing your workspace

Delete (remove)

Visual hash buckets with separate chaining collision handling

Add entries first:

Delete by key:

Hash Table (Size: 8)

Collisions: 0

bucket[0]

empty

bucket[1]

empty

bucket[2]

empty

bucket[3]

empty

bucket[4]

empty

bucket[5]

empty

bucket[6]

empty

bucket[7]

empty

Hash Function: sum of char codes % 8. Collision handling: Separate Chaining.

What is HashMap Delete?

HashMap Delete operation removes a key-value pair from the hash table. It uses the hash function to locate the bucket index, then searches the bucket for the key and removes it.

Delete Operation Steps

Call delete("age")
Compute hash("age") = 5 → go to index 5
Search bucket at index 5 for key "age"
Key found → remove from bucket
If key not found → return null/false

Time Complexity (Average): O(1)
Time Complexity (Worst): O(n)
Space Complexity: O(1)

Time Complexity Analysis

Edge Cases

Key not found: Returns null or false without modifying the table
Collision chain: Only the matching key is removed, others in chain remain

Real-world Applications

Removing expired cache entries
Unregistering event listeners
Removing user sessions
Dynamic symbol table management in compilers

Delete is a fundamental HashMap operation with O(1) average time complexity, making it highly efficient for dynamic data management.

// HashMap Delete in JavaScript
const hashMap = new Map();

// Insert some entries
hashMap.set("name", "Alice");
hashMap.set("age", 25);
hashMap.set("city", "New York");

// Delete a key
hashMap.delete("age");

// Verify deletion
console.log(hashMap.has("age")); // false
console.log(hashMap.size); // 2

Explore other operations

Insert

Delete (remove)

Visual hash buckets with separate chaining collision handling

Add entries first:

Delete by key:

Hash Table (Size: 8)

Collisions: 0

bucket[0]

empty

bucket[1]

empty

bucket[2]

empty

bucket[3]

empty

bucket[4]

empty

bucket[5]

empty

bucket[6]

empty

bucket[7]

empty

Hash Function: sum of char codes % 8. Collision handling: Separate Chaining.

What is HashMap Delete?

HashMap Delete operation removes a key-value pair from the hash table. It uses the hash function to locate the bucket index, then searches the bucket for the key and removes it.

Delete Operation Steps

Call delete("age")
Compute hash("age") = 5 → go to index 5
Search bucket at index 5 for key "age"
Key found → remove from bucket
If key not found → return null/false

Time Complexity (Average): O(1)
Time Complexity (Worst): O(n)
Space Complexity: O(1)

Time Complexity Analysis

Edge Cases

Key not found: Returns null or false without modifying the table
Collision chain: Only the matching key is removed, others in chain remain

Real-world Applications

Removing expired cache entries
Unregistering event listeners
Removing user sessions
Dynamic symbol table management in compilers

Delete is a fundamental HashMap operation with O(1) average time complexity, making it highly efficient for dynamic data management.

// HashMap Delete in JavaScript
const hashMap = new Map();

// Insert some entries
hashMap.set("name", "Alice");
hashMap.set("age", 25);
hashMap.set("city", "New York");

// Delete a key
hashMap.delete("age");

// Verify deletion
console.log(hashMap.has("age")); // false
console.log(hashMap.size); // 2

Explore other operations

Insert