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1
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0answers
21 views

retrieve file format from unknown binary file [closed]

Is it possible, somehow, maybe by using some kind of brute force algorithm, to try and figure out what kind of file one is dealing with when one only has the raw binary without file format or meta ...
2
votes
1answer
103 views

Finding median of three sorted array (the same length)

I think about following problem: There are given three sorted arrays $A,B,C$ (each of them is length $n$). Every array has distinct elements. Find median of union $A,B,C$. I consider following ...
1
vote
1answer
135 views

I know Binary Search is more efficient than Ternary search, but my results are opposite. Help interpreting results?

I have a piece of code that applies recursive Binary and Ternary searches on sorted arrays of increasing size, i.e. 500, 1000, 2000, 4000, etc. The entire code segment is about 200 lines so I've been ...
0
votes
0answers
25 views

Fast Raytracing Algorithm or Alternative needed

I have a grid that shows the world and its coastlines. An excerpt from the area around the UK is shown here From an arbitrary origin point anywhere in the ocean, I want to find those coastline ...
-1
votes
5answers
210 views

How can there be 10 steps in the binary search algorithm for the phone book search problem?

The following example was given in an online lecture I was watching. A phone directory is 1000 pages long, and we have to find the name "Zurich Smith". The algorithm is as follows: Split the phone ...
1
vote
0answers
18 views

Fractional cascading vs merge [closed]

Fractional cascading allows me to search in k ordered lists. It requires every list to have same ordering (how would I otherwise insert elements from the cascade below, preserving order?). But why is ...
3
votes
1answer
42 views

Finding the number of $L\leq j\leq R$ such that $a[j] \leq a[i]$

I have recently encountered the following problem which I heard can be solved by using BIT (binary indexed trees) but I am not sure how: Given an array $a[1, 2, \ldots, n]$ and $Q$ queries of the ...
-1
votes
1answer
66 views

augmenting AVL, intervals

Show how to augment dictionary of intervals (insert, delete, search) in order to make possible answer to following questions: Check if given interval $[a, b]$ intersects with some interval in a ...
0
votes
0answers
52 views

Find the index of minimum number that is greater than key given of a sorted array, does these two functions return same result?

Give an array of integer has been sorted (non-decreasing order), we need find the index of minimum number number that is greater than key given, I wrote two functions, they're identical except the ...
0
votes
1answer
64 views

Order a list of edges to make the the complexity of searching for an edge O(lg E)

I was reading this article on how to represent graphs, and probably the simplest way to think about it is to have a list of edges, with an edget being usually a list of the vertices that are related ...
2
votes
0answers
32 views

Two flavors of red-black trees with different performance

I've implemented two red-black trees (using the pseudo-code in CLRS) with slightly different flavors: 1) In the first tree, all the data is stored in the leaves. 2) In the second tree, the data is ...
6
votes
1answer
227 views

Optimize binary search on Segment Tree by storing past result

Goal Let $A[n]$ be an arbitrary array of integers of length $n$. Let $S$ be a segment tree, represented by an array of records: each record containing the left and right bounds ($[l,r]$) of the ...
2
votes
1answer
622 views

Potential method for dynamic binary search

I'm trying to solve 17-2(b) problem from Cormen(CLRS) using potential method. Problem from Cormen: 17-2 Making binary search dynamic Binary search of a sorted array takes logarithmic search time, ...
3
votes
2answers
415 views

first intersection of two arrays of integers - double binary search feasible?

I'm interested to find the fastest possible way to find the first element of an intersection of two integers arrays (first match) Looking for the 'fastest' algorithm I have seen different methods ...
1
vote
1answer
51 views

Finding Triples that satisfy modulo equation in $O(n\log n)$ time

Given $n$, I am trying to count the number of values $(a,b,c)$ that satisfy the following equation in $O(n\log n)$ time. I do not need the values themselves only the number of total values that ...
1
vote
2answers
17 views

Order of storage of pointers for a linked list of length n

I have a linked list in which I have kept the elements in order (increasing/decreasing). I want to be able to perform a binary search on this linked list. For this I am keeping pointers to the middle ...
0
votes
1answer
5k views

Proving that the average case complexity of binary search is O(log n)

I know that the both the average and worst case complexity of binary search is O(log n) and I know how to prove the worst case complexity is O(log n) using recurrence relations. But how would I go ...
5
votes
2answers
436 views

Compute square root using (bit) additions and shifts as primitives

Question: Given an $n$-bit natural number $N$, how to compute $\lceil \sqrt{N} \rceil$ using only $O(n)$ (bit) additions and shifts? The tip is to use binary search. However, I could not achieve ...
33
votes
3answers
10k views

Why is binary search faster than ternary search?

Searching an array of $N$ elements using binary search takes, in the worst case $\log_2 N$ iterations because, at each step we trim half of our search space. If, instead, we used 'ternary search', ...
3
votes
3answers
118 views

Minimum number of tests to identify subset of modules that trigger a bug?

I have an ordered set of $M$ software modules compiled together. The interaction of some $N$-tuple of these modules is causing a bug when the program is run. I can run the program with any desired ...
1
vote
2answers
202 views

Searching for a string of numbers in a large digit sequence [closed]

How would one search for a string of digits in a large digit sequence? For example, I'd like to search for 351814 in Euler's number. I'm not too keen on computer ...
0
votes
0answers
20 views

Uniform Binary Search explanation and lookup table [duplicate]

Please can anyone explain me the worst ,average and best case running time for the Unifrom binary search .. Also how can the lookup table be explained?
1
vote
0answers
90 views

Binary search transition point of a function on stream

Consider an unknown function $f(x,y)$, where $x$ and $y$ are just two scalar numbers in $[0,1]$. $f(x,y)$ is an increasing function of $y$ and is between $0$ and $1$ but is unknown. At each time I ...
-1
votes
2answers
135 views

BST Successor Proof

I'm studying for my CS final and I can't seem to get the anywhere with one of the questions. This is the question: Prove that if a node in a BST has a successor, but has no right child, then its ...
1
vote
1answer
2k views

How to analyze/test a binary search algorithm?

I was asked to "Compute the average runtime for a binary search, ordered array, and the key is in the array." I'm not quite sure how to approach this problem. Isn't the runtime of binary search O(log ...
4
votes
1answer
162 views

Searching a value in a “piecewise” ordered array

If we have an array $A$ of length $N$, which is partitioned into $\sqrt{N}$ adjacent subarrays $A(i)$, each of which is monotonically ordered from $\min(i)$ to $\max(i)$ (it is known what places have ...
2
votes
1answer
73 views

Finding a '1' cell with a '0' to its right in a binary array

Given an array of size n that holds ones and zeros I need to find an index of a 1 cell that has 0 to his right (in then next ...