# Questions tagged [streaming-algorithm]

Streaming reads the data once, in sequence.

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### Is every linear-time algorithm a streaming algorithm?

Over at this question about inversion counting, I found a paper that proves a lower bound on space complexity for all (exact) streaming algorithms. I have claimed that this bound extends to all linear ...
983 views

### Counting islands in Boolean matrices

Given an $n \times m$ Boolean matrix $\mathrm X$, let $0$ entries represent the sea and $1$ entries represent land. Define an island as vertically or horizontally (but not diagonally) adjacent $1$ ...
157 views

### Streaming algorithm and random access

Consider an array $X$ of $n$ cells, each containing a number from $\{1,..., n\}$. There is at least one duplicate number, i.e., a number that appears at least twice. I want output some duplicate ...
1k views

### What is the correct way to determine the width and depth of a count-min sketch?

The width (number of registers) and depth (number of hash functions) of a Count-Min sketch determine the accuracy of counts retrieved. I've found two different methods for calculating the width ($w$) ...
1k views

### Space complexity for finding the minimum number outside the list of numbers

We are given an (unsorted) list $L=(a_1,\dots,a_n)$ of numbers of size $n$, where $a_i\in \{ 1,\dots,B\}$. We want to find the minimum number $x$ from $\{ 1,\dots,B\} \backslash L$. What is the ...
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### Flajolet-Martin Algorithm : question about use of certain hash functions

this is a question given in a PDF about streaming algorithms (this isnt an assignment but im trying to understand) Exercise 4.4.1 : Suppose our stream consists of the integers 3, 1, 4, 1, 5, 9, 2,...
86 views

### What are some of the simplest applications of heavy hitter problem?

I am learning about stream algorithms and am implementing Count-Min sketch data structure. I am also learning to approximately solve the HH problem with sublinear space complexity. I want to know ...
78 views

### Different properties of Heavy-Hitters and Count-Min Sketch algorithms?

I'm currently using the Heavy-Hitters algorithm as described here and I'm wondering what if any space, time, accuracy, or real-world performance differences I would see if I were to switch to an ...
421 views

### How much better are conservative updates for count-min sketch?

I've been reading about count-min sketch and I'm interested in the performance of this data structure when doing conservative updates. To my understanding from the Wikipedia article, conservative ...
117 views

### What does 'buffering' mean?

I read the lecture 4 of CS162 (UC Berkeley: https://inst.eecs.berkeley.edu/~cs162/sp17/static/lectures/4.pdf), but I got little bit confused about the meaning of the keyword "buffered" they used when ...
157 views

### Optimal data structure for a time-windowed streaming graph in order to compute fast statistics

I apologize if this is the wrong place or too trivial a question for this community. What is the best data structure to store a time-windowed streaming graph in order to compute fast statistics over ...
111 views

### sliding window maximum

I have a stream of tuples arriving in the following form: (timestamp,price). There is no pattern in the arrival of these data points (number of data points per minute is random). I need to be able to ...
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### Efficient streaming sort

Consider following task: we have an input of N+1 lines, where first line contains N - number of items, and then we have N lines, each one contains one item, which is a tuple (number id, number m), id &...
419 views

### Algorithm for finding 2 missing items in a stream of integers

I saw this post and wondered why the approach described in the accepted answer works. The same problem and solution is described a bit nicer here. So let's say we receive a stream of $n-2$ pairwise ...
118 views

### Proof of Lower Bound for Deterministic Distinct Elements Algorithm

There is a proof in this document (page 8, Section 4, Lemma 3: https://inst.eecs.berkeley.edu/~cs170/fa16/lecture-11-29.pdf) that mirrors a proof my professor gave in my algorithms class. The lemma ...
270 views

### What is the best stream data clustering algorithm that can handle non-static, uncertain data? [closed]

I have gone through many algorithms including streaming k-means, CluStream etc and they all have their pros and cons. What is the best performing algorithm in terms of Computational Complexity ...
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### What resources are there for students to compute on a data stream?

I teach a randomized algorithms course, and many of the cool applications are to streaming computation. I can have students implement these algorithms in Python or C++, but I feel it would be much ...
166 views

### What data structure is best suited for nested values and count of values?

I have incoming stream of data which has following values. Country, City, State Along with maximum number of unique values to store (e.g. 50,22,12). I need to design a system which will keep count of ...
183 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 ...
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### Streaming Knapsack Problem

I want to implement efficiently "streaming Knapsack" problem in java. The problem is I have a stream input of integer data coming continuously for example -1, 2, 9, 5, 5, 11, 1 -3,... The question ...
176 views

### Is there a fast algorithm for computing the rolling mode of an array of integers?

I was wondering if there exists an efficient algorithm for calculating the "rolling mode of an array of integers. By rolling mode I mean that we have an array of integers of size $n$ and a sliding ...
3k views

### Find pth percentile of a stream of numbers

I want to find the pth percentile of a stream of integers, exactly (not approximately). If we know the number of integers which will be coming in the stream and the numbers can fit into the memory ...
31 views

### 1-sparse recovery algorithm

In the reference below, a 1-sparse recovery algorithm over a vector $a \in R^n$ is defined as follows. My question is why do we need the modulus (i.e. $x \mod p$)? Algorithm: Keep track of  \...
Given a sequence $x \in \{ 1,2,3...,\vert \Sigma \vert \}^*$ one wants to create a sketch of it say $s(x)$ of size $\frac{2c}{3}k (ln^2 k)$ bits. And that seems to be achieved as follows, pick at ...