Table of Contents
Can you have a for loop inside a for loop?
Nested For Loops. When a loop is nested inside another loop, the inner loop runs many times inside the outer loop. In each iteration of the outer loop, the inner loop will be re-started.
Are nested for loops bad?
Nested loops are frequently (but not always) bad practice, because they’re frequently (but not always) overkill for what you’re trying to do. In many cases, there’s a much faster and less wasteful way to accomplish the goal you’re trying to achieve.
Are nested for loops bad python?
Foreword. Nested loops are not a bad thing per se. They are only bad, if there are used for problems, for which better algorithm have been found (better and bad in terms of efficiency regarding the input size). Sorting of a list of integers for example is such a problem.
Can I have while loop inside a while loop?
The loop which contains a loop inside a loop is known as the nested loop. It can contain the for loop inside a for loop or a while loop inside a while loop. It is also possible that a while loop can contain the for loop and vice-versa.
How do you exit an inner loop in Python?
Approach 3: Using a flag variable The outer loop must contain an if block after the inner loop. The if block must check the value of the flag variable and contain a break statement. If the flag variable is True, then the if block will be executed and will break out of the inner loop also.
Can for loop contain another for look?
Yes, a for loop can contain another for loop.
When should you use nested loops?
Nested loops are useful when for each pass through the outer loop, you need to repeat some action on the data in the outer loop. For example, you read a file line by line and for each line you must count how many times the word “the” is found.
How many nested loops is too many?
There are no limits. Or, more precisely, there are no maximum limits on the user. There are minimum limits on the compiler, however. So you can have 127 nested loops/if/switch and 12-dimensional arrays and be sure that any compliant compiler will be able to compile you.
Can I put while inside while?
A nested while loop is a while statement inside another while statement. The execution of the inner loop continues till the condition described in the inner loop is satisfied. Once the condition of the inner loop is satisfied, the program moves to the next iteration of the outer loop.
Do nested loops give a big O notation?
Yes, nested loops are one way to quickly get a big O notation. Typically (but not always) one loop nested in another will cause O (n²). Think about it, the inner loop is executed i times, for each value of i .
How do you get big O notation?
Yes, nested loops are one way to quickly get a big O notation. Typically (but not always) one loop nested in another will cause O (n²). Think about it, the inner loop is executed i times, for each value of i . The outer loop is executed n times.
What if the complexity of an inner loop is O(n)?
If it were in fact O(N), then our overall complexity becomes O(N^3). Think of it as multiplication (because it is). For ~N outer loop iterations, the inner loop iterates ~N times, with each iteration performing ~N work. N times N times N = N^3.
What is the O(n×n) of an outer loop?
The outer loop does the inner loop ntimes, so it is O(n× n), or O(n2 ). In general, if the number of iterations a loop makes is dependant on the size of the input, it is O(n). And if ksuch loops are nested, it is O(nk ). Share Improve this answer Follow edited Sep 26 ’11 at 2:53 Jon Purdy