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-1
votes
1answer
36 views

Proving correctness of a loop that calculates the sum of array

I am trying to mathematically prove that the following program is correct: ...
0
votes
0answers
20 views

Counter stops after one incrementation during a for loop [closed]

The algorithm I'm writing right now is kind of messy, but I don't have much time to fix it before I need to use it tonight. Basically, I'm iterating through an Arraylist of Strings and comparing each ...
5
votes
1answer
240 views

From Guido's essays, how does this function avoid quadratic behavior in a string concatenation algorithm?

I am reading one of Guido van Rossum's essays on optimization in Python. We are interested in converting a Python list of integers to their character equivalents. Here's the straightforward ...
2
votes
2answers
61 views

Recurrence relations when function call is made inside loop

int fun (int n) { int x=1, k; if (n==1) return x; for (k=1; k<n; ++k) x = x + fun(k) * fun(n – k); return x; } What is the value of fun(5)? I ...
2
votes
0answers
17 views

What would be the time complexity if a recursive function is inside a loop? [duplicate]

I am confused in calculating the time complexity for a recursive function inside a loop. ...
2
votes
1answer
59 views

Can a vectorized computation always be parallelized?

If the question appears vague, I'll gladly clarify. It's not tied to a programing language. If there is a language dependency in the answer, one can place it in the context of Python, R, VB, ...
2
votes
0answers
42 views

How can I use nested loops to print out this triangle word pattern? [closed]

I'm trying to make a pattern that looks like this: And am given this code to start: ...
7
votes
2answers
126 views

Loop variant for a while loop that occasionally doesn't decrease?

I'm working on practice problems for a test I have, and every example of loop variant decreased with every iteration of the loop. On this one, the values remain the same when a < b. My attempts ...
-1
votes
1answer
52 views
0
votes
1answer
34 views

run time analysis of a for loop [duplicate]

I am trying to prepare for a test comping up on run-time analysis. I have been hit with a for loop that is throwing me a bit. I am hoping someone can help me. the loop is ...
14
votes
1answer
314 views

Does a do-while loop suffice for Turing-completeness?

I know that, in imperative programming languages, a while-do loop is sufficient as a control flow construct to make the language Turing-complete (as far as control flow goes - of course we also need ...
2
votes
5answers
294 views

Do recursive algorithms generally perform better than their for-loop counterpart?

I'm sure this is not a challenge for you but it remains an open question for me: Is it wise to prefer a recursive algorithm over its for-loop counterpart? E.g. take the evaluation of the natural ...
4
votes
4answers
653 views

Loops at low level

When programming with high level languages like Python or Matlab, it is always better to model the problem such as the solution is some kind of vector or matrix multiplication, to avoid loops. But ...
0
votes
1answer
90 views

Why are functional programs considered slower than procedural counterparts asymptotically, if the opposite appears true?

I've read and been told way too many times that functional algorithms and data structures have an obligatory O(log(N)) slowdown in respect to their procedural ...
3
votes
1answer
80 views

Running time function for an algorithm with while and for loop

I have trouble determining the running time function for algorithm below. I know that there are initially two assignment operations, int i=n and ...
1
vote
1answer
365 views

provability of while loop vs for loop [closed]

I'm abit afraid to ask this question here seeing as I asked it on programmers SE already, the thing is I think the question is more about the underlying theory than the use in practice (or call it ...
0
votes
1answer
57 views

Algorithm analysis of nested loop [duplicate]

so I have this code: for (int i=1; i < n; i=i*5) for (j=i; j < n; j++) sum = i+j; And I'm wondering, what's the time complexity of this for ...
2
votes
1answer
77 views

Simplifying a nested sum

I'm trying to analyze an algorithm of a function, I can express the function in term of summation, but I have no clues on how I could simplify this summation down to get the run-time in tern of big ...
0
votes
0answers
15 views

Runtime of this loop [duplicate]

I need some advice on how to determine the runtime of this loop : s=0 for ( i=1 , i <= 2^m ; i=i*2 ) { s++ } return s With $C_1$ = actions ...
-1
votes
1answer
50 views

What is the time complexity (big O) of this nested for-loop? [duplicate]

What is the time complexity (big O) of this nested for-loop? I believe it's either O(n) or O(n^2) ...
0
votes
1answer
140 views

Finding a Hoare logic correctness proof for a Repeat-Until loop

How can we prove a program in repeat until using Hoare Logic? I've found a rule like this: {P} S {R}, {R ^ ~B -> P}, {R ^ B -> Q} for ...
0
votes
0answers
16 views

Confusion with space and time usage [duplicate]

The following is my own set-up code: ...
1
vote
1answer
50 views

Big-O Time Complexity of nested for loops [duplicate]

My gut tells me the time-complexity of the following code is simply O(n^2). However, I'm not convinced, thinking it could possibly be O(n^3): ...
4
votes
2answers
141 views

How to bridge theory and implementation for while loops?

I'm working on my own little programming language for educational purposes, and I've run into a little bit of a problem. There are a few different solutions for it, but all of them seem inelegant - ...
-2
votes
1answer
196 views

Complexity Analysis for a nested loop with two methods [duplicate]

Hey I am studying for my intro algorithms class final and I'm not sure if I'm understanding this question correctly (its from a sample final exam). If someone could explain this to me that would be ...
0
votes
0answers
23 views

Nested Loop Complexity [duplicate]

I have several lists of varying size, each index of the list contains both a key and an object : list1.add('Key', obj). The lists are all sorted. My aim is to iterate through the list and match 1 or ...
1
vote
1answer
80 views

Loop invariant: decreasing a variable and swapping it

As an example exercise, we were asked to find the loop invariant for this bit of code. ...
-1
votes
1answer
240 views

Runtime of nested loops

What is the asymptotic runtime of fthe ollowing piece of code in terms of number of updates to S in worst case. ...
0
votes
0answers
17 views

Big o notation for the algo [duplicate]

Asked this at programmers Stack Exchange, was recommend to ask here : What would be the big o for the algo: for (i=0; i < n*n; i++) for(j=0; j<i*i; j++) ...
1
vote
1answer
110 views

Explanation of the complexity of a loop [duplicate]

I am confused on the following: In the following trivial code: ...
0
votes
2answers
115 views

What is the Big O estimate of a nested for loop?

I am trying to figure out what the big o estimate of the following for loop is. ...
0
votes
0answers
19 views

Time complexity of complex nested for loops [duplicate]

What are the time complexities of the following code? I posted this on the general stackexchange website, but it was suggested that I post it here. ...
1
vote
0answers
26 views

Complexity of a nested for loop [duplicate]

I'm trying to work through various exercises in Skiena's "Algorithm Design Manual." One problem that I am stuck on is as follows: What value is returned by the following function? Express your ...
0
votes
3answers
306 views

Calculating time complexity of two interdependent nested for loops

Consider the following code segment : for (int i = 1; i <= n; i++ ) { for (int j = 1; j <= n; j = j + i ) { printf("Hi"); } } Here, the ...
0
votes
2answers
43 views

make Magic Square? [closed]

I need to write a function that takes in a 2D list, that is a NEARLY magic square, meaning that if you perform ONE swap, it becomes a magic square. The function would take in this nearly magic square, ...
1
vote
1answer
418 views
1
vote
1answer
541 views

Sum number of times statement is executed in triple nested loop

I have this code fragment: for( i=0; i<n; i++ ) for( j=0; j<i; j++ ) for( k=0; k<j; k++ ) S; I need to find the number of times ...
3
votes
3answers
2k views

What is the asymptotic runtime of this nested loop? [duplicate]

I am trying to analyse the runtime of this algorithm: for(i=1; i < n; i++){ for(j=1; j <= i; j++){ statement1; } } Expanding the ...
3
votes
1answer
256 views

Theta Runtime of Nested for Loops

I have two for loops, one nested within the other. I have two int variables n and U, where U > n. I know that the outer loop runs exactly U times (pretty much ...
1
vote
1answer
209 views

Can a Turing machine decide if a LOOP program stops for the integer input 0

This is a question I found in a practice exam while I am preparing for my mid term exam. The answer needs justification, either a pseudo code or a logical explanation why not. What puzzled me about ...
1
vote
1answer
147 views

Is it possible to write a universal loop program for if-then & loop programs and it is possible to write a universal while program for while progra

Is it possible to write a universal loop program for if-then & loop programs and it is possible to write a universal while program for while programs? Long version and some background: Before ...
0
votes
1answer
87 views

Confusion related to calculating time complexity

I have some confusion related to calculating the time complexity of this algorithm opt(i) for j=i:n a = f(i,j) + opt(j+1) end How is the running ...
3
votes
2answers
565 views

Analyzing programs with multiple for-loops

If they were all linked to make a condition such as ($1 < i < j < k < n$), I know how to solve, but the last loop is disconnected so I have no clue on how to do these... the ones like ...
2
votes
1answer
4k views

Triple nested for-loops [duplicate]

Possible Duplicate: A puzzle related to nested loops I am trying to count the exact/total number of iterations the following nested for-loops are executed: ...
0
votes
2answers
330 views

A puzzle related to nested loops

For a given input $N$, how many times does the enclosed statement executes? for $i$ in $1\ldots N$ loop $\quad$for $j$ in $1\ldots i$ loop $\quad$$\quad$for $k$ in $i\ldots j$ loop ...
1
vote
2answers
1k views

Runtime analysis of a nested loop

I have some difficulties performing the worst case analysis on this algorithm. The outermost loop is executed $2N$ times. The while loop, in the worst case, will increase by $2$ each time, so it ...
1
vote
1answer
450 views

Asymptotic time complexity of a two-loop program

I have two pieces of code in a function which I'm trying to calculate the asymptotic running time for: ...
3
votes
2answers
5k views

Time complexity formula of nested loops

I've just begun this stage 2 Compsci paper on algorithms, and stuff like this is not my strong point. I've come across this in my lecture slides. ...