You need to identify the first non-repeating character in a string. How can a hashmap be utilized to solve this problem efficiently?
Use the hashmap to store the unique characters of the string, then iterate through the hashmap to find the first non-repeating character.
A hashmap cannot be used efficiently for this problem.
Store the characters of the string as keys in the hashmap, and their positions as values. The first character with the lowest position value is the first non-repeating character.
Store the frequency of each character in the hashmap, then iterate through the string and return the first character with a frequency of 1.
What is the purpose of dynamic resizing (rehashing) in a hashmap?
To increase the size of the hash function's output range.
To reduce the number of keys stored in the hashmap.
To maintain a low load factor and prevent performance degradation.
To improve the efficiency of key deletion operations.
In a hash table using open addressing with quadratic probing, if the initial hash function maps a key to index 'i', and a collision occurs, what is the index probed in the second attempt (assuming table size 'm')?
(i * 2) % m
(i + 4) % m
(i + 2) % m
(i + 1) % m
How does quadratic probing aim to mitigate the clustering problem in open addressing?
By using a second hash function to determine the probe sequence
By probing linearly with a fixed step size
By probing with quadratically increasing intervals
By probing with exponentially increasing intervals
What is a significant disadvantage of using a fixed-size hash table in conjunction with a hash function prone to collisions?
Increased memory usage due to the fixed size allocation
Inability to store data that exceeds the pre-defined table size
Complexity in implementing the hash function itself
Degraded performance due to chaining or open addressing for collision resolution
When choosing a collision resolution strategy for a hash table, which factors are essential to consider?
Programming language and hardware architecture
All of the above
Size of the keys and values being stored
Expected data distribution and load factor
Which of the following scenarios could potentially lead to collisions in a hashmap?
Having a hash table size much larger than the number of keys being stored
Using a hash function that distributes keys evenly across the hash table
Storing keys with a wide range of values
Hashing two different keys to the same index in the hash table
In the worst-case scenario, what is the time complexity of searching for a key in a hashmap?
O(log n)
O(n)
O(n log n)
O(1)
When does rehashing typically occur in a hashmap?
When the hashmap is cleared using the clear() method.
When the load factor exceeds a predetermined threshold.
Every time a new key is inserted.
When the hash function is modified.
What is the significance of the output size of a cryptographic hash function?
Influences the memory required to store the hash function
Determines the speed of hash computation
Affects the uniqueness of the hash for different inputs
Impacts the resistance against brute-force attacks