Java loop - how many simple operations?

Question

How many simple operations are performed in a simple java loop?

int result = 0;
for (int i = 0; i <= n; i++) {
    result = result + i;
}

We discussed in class and agreed on somewhat 8n+13 simple operations, but it would be nice with a correct, documented result. Thanks.

@MarounMaroun, he's calculating the complexity in terms of simple operations, which is not the limiting behavior of the function, but the count of the operations like *addition*, *assingment* and so on. — Konstantin Yovkov, Feb 10 '15 at 08:34
Stackoverflow isn't for "ey boys! Make my home works". What exactly you don't understand? What have you tried? — PhoneixS, Feb 10 '15 at 08:35

score 2 · Answer 1 · answered Feb 10 '15 at 08:34

2

It's O(n). All other fancy 8n +13 can be just reduced to regular O(n)

answered Feb 10 '15 at 08:34

Marcin Szymczak

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score 1 · Answer 2 · answered Feb 10 '15 at 08:36

It will be O(n)

O(n): Time Complexity of a loop is considered as O(n) if the loop variables is incremented / decremented by a constant amount. For example following functions have O(n) time complexity.

Example

 // Here c is a positive integer constant   
   for (int i = 1; i <= n; i += c) {  
        // some O(1) expressions
   }

   for (int i = n; i > 0; i -= c) {
        // some O(1) expressions
   }

In your case i and result is incrementing by constant rate .

score 0 · Answer 3 · answered Feb 10 '15 at 08:44

I think you ask about the complexity in terms of number of operations (not the order of magnitude) so I think first is to divide it to small operations and then make the calculation:

int result = 0; // 1 op
int i = 0; // 1op
while (i <= n) { // n op of comparison
    result + i; // n op (1 op * n because is inside the loop)
    result = [result of operation]; // n op 
    i + 1 // n op
    i = [result of operation]; // n op
}

So you have 5n+2 operations that is O(n) magnitude. Get in mind (as you can see in other questions) that the important thing is normally to get only the order of magnitude.

Also you can have the while divided more in a compassion and a jump. And assignments and declarations can been split.

score -1 · Answer 4 · edited Feb 10 '15 at 08:39

-1

Its O(n) . Performance is measured in terms of Big oh O . O(0) is better performing than O(1). O(n) means which consumes more time and hence require more processing time, where n is the number of iterations.

edited Feb 10 '15 at 08:39

Alexis King

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answered Feb 10 '15 at 08:36

SabaRish

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What is this mystical `O(0)` you speak of and how can I achieve it? – Alexis King Feb 10 '15 at 08:38
Always try to add the important information in answer not in comments ! – Neeraj Jain Feb 10 '15 at 08:41

Java loop - how many simple operations?

4 Answers4