How to Identify Cycles in an Object Hierarchy?

What are the best techniques to find cycles in an object hierarchy?

// Sample JavaScript implementation for cycle detection in an object hierarchy
function hasCycle(obj, visited = new Set()) {
    if (!obj || typeof obj !== 'object') return false;
    if (visited.has(obj)) return true;
    visited.add(obj);
    for (const key in obj) {
        if (hasCycle(obj[key], visited)) {
            return true;
        }
    }
    visited.delete(obj);
    return false;
}

Detecting cycles in an object hierarchy is crucial for avoiding infinite loops in data structures. This can occur when objects reference each other in a way that creates a loop. Here’s a structured breakdown of how to identify cycles.

// Example of using a depth-first search algorithm to check for cycles
function detectCycles(obj, visited = new Set()) {
    if (typeof obj !== 'object' || obj === null) return false;
    if (visited.has(obj)) return true;
    visited.add(obj);
    for (const key in obj) {
        if (detectCycles(obj[key], visited)) {
            return true;
        }
    }
    visited.delete(obj);
    return false;
}

Causes

• Cyclic references in object properties.
• Linked data structures such as graphs that inherently contain loops.

Solutions

• Utilize depth-first search (DFS) with a set to track visited objects.
• Implement a slow and fast pointer technique to detect cycles efficiently.

Mistake: Failing to reset or clear the visited set after the function call.

Solution: Ensure the visited set is either unique to each call or reset at the end to prevent false positives.

Mistake: Not handling edge cases such as null or non-object types.

Solution: Always check if the input is a valid object before proceeding.