Nested loop

Definition

A nested loop is a loop inside another loop. The inner loop runs completely every time the outer loop runs once.

5 Must Know Facts For Your Next Test

1. A nested loop can have any number of levels; each level represents a deeper layer of looping.
2. Common use cases include iterating over multi-dimensional arrays or matrices.
3. The total number of iterations for the inner loop is the product of the outer and inner loops' iteration counts.
4. Nested loops can significantly increase the time complexity of an algorithm, often resulting in quadratic or cubic complexity.
5. Python supports nesting any type of loop (for, while) within another.

Review Questions

• What happens to the inner loop when the outer loop runs?
• Give an example where nested loops might be necessary.
• How does nesting loops affect the overall time complexity?

Related terms

Loop: A sequence of instructions that repeats until a certain condition is met.

Time Complexity: A measure indicating how the runtime of an algorithm grows relative to input size.

Multi-dimensional Array: An array containing more than one dimension, such as a matrix, which can be traversed with nested loops.