Write functions `union(a, b)`, `intersect(a, b)`, and `difference(a, b)` for arrays treated as sets.

Problem Statement

<p>Write functions <code>union(a, b)</code>, <code>intersect(a, b)</code>, and <code>difference(a, b)</code> for arrays treated as sets.</p>

Examples

Input: union([1, 2], [2, 3]); intersect([1, 2], [2, 3]); difference([1, 2], [2, 3])

Output: union: [1,2,3], intersect: [2], diff: [1]

Explanation: Standard set algebraic operations.

Complexity

Time Complexity: O(N)

Space Complexity: O(1)

Hints

💡 Hint 1: Use Set for efficient lookups. 💡 Hint 2: Union: combine both. Intersect: elements in both. Difference: elements in a but not in b. 💡 Hint 3: Convert to Sets and use filter/spread for each operation.

Editorial & Approach

Problem Overview & Intuition

To solve Implement Set Operations, we consider the execution characteristics of JavaScript engines. Write functions `union(a, b)`, `intersect(a, b)`, and `difference(a, b)` for arrays treated as sets. By utilizing idiomatic language constructs and clean algorithmic principles, we can accomplish this with optimal time and memory usage.

Step-by-Step Approach

Understand Problem Contract: Identify input arguments, return type expectations, and edge cases (empty inputs, nullish values).
Choose Core Mechanism: Use modern JavaScript patterns (use set for efficient lookups).
Implement Logic: Handle state and transformations efficiently (union: combine both. intersect: elements in both. difference: elements in a but not in b).
Return Result: Ensure proper return format and preserve caller context if applicable.

Optimal Implementation (JavaScript)

function setOps(a, b) {
  const setA = new Set(a);
  const setB = new Set(b);
  return {
    union: [...new Set([...a, ...b])],
    intersect: a.filter(x => setB.has(x)),
    difference: a.filter(x => !setB.has(x))
  };
}

Complexity Analysis

Time Complexity O(N) linear scan over input

Space Complexity O(1) constant auxiliary space (or O(N) output)

Edge Cases & Corner Traps Handled

Empty or boundary inputs (empty arrays, strings, zero length).
Type checks and unexpected values (e.g. null, undefined, negative numbers).
Closure preservation and memory isolation between separate invocations.

Implement Set Operations

Medium

Write functions union(a, b), intersect(a, b), and difference(a, b) for arrays treated as sets.

Example Scenarios

1Example 1

Input: union([1, 2], [2, 3]); intersect([1, 2], [2, 3]); difference([1, 2], [2, 3])

Output: union: [1,2,3], intersect: [2], diff: [1]

Explanation:

Standard set algebraic operations.

Editor

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{"union":[1,2,3,4,5,6],"intersect":[3,4],"difference":[1,2]}