Iteration vs Recursion

Both iteration and recursion are programming techniques used for repeating a set of instructions. Although they often can be used to solve the same problems, they have distinct characteristics and use-cases.

Let’s explore the two concepts with examples in Java.

Iteration

Iteration uses looping constructs like for, while, or do-while to repeatedly execute a block of code.

Example: Factorial using Iteration

public static int factorialIterative(int n) {
    int result = 1;
    for (int i = 1; i <= n; i++) {
        result *= i;
    }
    return result;
}

Recursion

Recursion is a technique where a function calls itself to solve a smaller instance of the same problem.

Example: Factorial using Recursion

public static int factorialRecursive(int n) {
    // base case
    if (n == 0) {
        return 1;
    }
    // recursive case
    return n * factorialRecursive(n - 1);
}

Comparison

Readability

• Iteration: Generally easier to understand for simple loops.
• Recursion: Can simplify complex problems into more readable code.

Performance

• Iteration: Usually faster and less memory-intensive.
• Recursion: Can be slower and more memory-intensive due to function call overhead.

Use-Cases

• Iteration: Best for simple loops and when you need fine-grained control over loop variables.
• Recursion: Useful for divide-and-conquer, tree traversal, and problems requiring backtracking.

Debugging

• Iteration: Easier to debug because of straightforward flow control.
• Recursion: Can be challenging to debug, especially for deep recursion levels.

Stack Overflow Risk

• Iteration: Generally no risk.
• Recursion: Risk of stack overflow for deep recursion or infinite recursion.