# Tag Info

### Floyd's Cycle detection algorithm | Determining the starting point of cycle

I have seen the accepted answer as proof elsewhere too. However, while its easy to grok, it is incorrect. What it proves is $x = z$ (which is obviously wrong, and the diagram just makes it seem ...
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### How to find middle element of linked list in one pass?

By cheating, and doing two passes at the same time, in parallel. But I do not know whether the recruiters will like this. Can be done on a single linked list, with a nice trick. Two pointers travel ...
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Linked lists can work well even if memory is fragmented. Arrays usually require a continuous piece of memory. For large piece of data finding this large continuous piece of memory might be hard. Most ...

### What is the time complexity of enqueue and dequeue of a queue implemented with a singly linked list?

Enqueueing You don't need to traverse the entire list to find the new tail, you just need to add a new node where the current tail points to and set that node as the new tail. Pseudocode (assuming ...
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This isn't really about "advantages", but appropriateness. Sometimes it's more appropriate to use an array, and sometimes to use a linked list. If it helps, take a look at this large table ...
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Accepted

### The origin of list data structure

Knuth gives a good overview on the history of lists and linked data structures. From The Art of Computer Programming, Volume I, Section 2.6: Linked memory techniques were really born when A. Newell,...
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Accepted

### Recursive definition of Matrix

Multiple Dimensions For a recursive counterpart for matrices, we need dependent types. Indeed, lists are one dimensional and so (horizontal) concatenation of lists is all that is needed. However, ...

### How to find middle element of linked list in one pass?

If it's not a doubly linked list, you could just count and use a list, but that requires doubling your memory in the worst case, and it simply won't work if the list is too large to store in memory. ...
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### What precisely/concisely is the "head" of a singly linked list? I ask bc of ambiguity online

You're right, there are many different definitions of a List/Linked List. No one definition is correct nor incorrect. This answer is a bit long-winded, but having a backstory on the logic behind lists ...
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### How to find middle element of linked list in one pass?

Elaborating on Hendrik's answer If it's a doubly linked list, iterate from both ends ...
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### Floyd's Cycle Detection Algorithm Proof In Laymen

The easiest way to understand this is really to draw it out and move your fingers on a graph, so I recommend literally pulling out a piece of paper to follow along. Picture the part before the cycle ...

If you make the elements stored in the list already contain the next/prev pointers (called an intrinsic or intrusive linked list) than the list doesn't need to do allocations and risk fragmenting ...
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An important consideration missing from the other answers: It's easier and more performant to use immutable linked lists than immutable arrays, which is especially important in functional programming ...
Accepted

### Correct way to implement linked list

First of all, don't have a head pointer in your structure that doesn't point to the head of the list: it will confuse everyone. Call the pointer in your structure <...
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I think this is due to the differences in the philosophy underlying the design of both programming languages. The C++ philosophy allows data structures to cause undefined behavior as soon as the user ...
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Accepted

### Measuring the length of a "loop" in a linked list in $O(n)$ Time?

There is a surprisingly simpler solution! Are you familiar with the tortoise and hare algorithm? Start thinking from there: Understand this algorithm and why it works, and then you might get an idea ...
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Accepted

### Why do we use multiple data structures?

Aspects other than asymptotic worst case time are also important. For example Actual speed in practice Memory consumption Implementation difficulty Algorithmic analysis almost never tells you the ...
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Accepted

### What is wasted space parameter and why is it O(n) for a linked list

Different people seem to define "wasted space" in different ways. Some authors define it as any space in a data structure that's not used to store actual data; others define it as space that could be ...
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### How to find middle element of linked list in one pass?

Create a structure with a pointer capable of pointing to nodes of linked list and with an integer variable which keeps count of the number of nodes in the list. ...
• 476

### Using B-method, and formal methods in general, to model and verify a reverse linked list

There are many approaches for verifying linked structures---arguably, more suitable than the B method---that you might want to use, depending on the language and properties you want to verify. Most of ...
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Accepted

### What is the complexity of finding the predecessor of a node in a doubly linked list?

Both answers look wrong. Time is indeed $O(1)$ because you can look into prev (not next) pointer of the node. The answers you ...
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### What is the time complexity of enqueue and dequeue of a queue implemented with a singly linked list?

The comment in the book apparently assumes that your linked list implementation maintains two pointers, head that points to the first node in the list, and ...
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### The origin of list data structure

The first use of linked lists in their modern form seems to have been by Peter Luhn in 1953, when he implemented a chaining-based hash table on the IBM 701 machine. Linked lists are often ...
Accepted

### Time complexity of insertion in linked list

The question only says that the target list needs to be maintained in sorted order. It doesn't say anything about any other data structure that you may choose to use. The proposed solution first does ...

• 307
Accepted

### What is the type of linked list where order doesn't matter

I took a look at the book you are referencing, and it does appear that Steven Skiena made an unordered Dictionary implemented as a linked list. It's not a terribly efficient data structure, but he ...
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