Letter Combinations of Phone Number

**Problem Statement:** Given the required input arguments, write an efficient algorithm to solve the **Letter Combinations of Phone Number** problem. Implement the required logic as specified by standard definitions for this classic algorithmic challenge. **Hint / Expected Approach:** Digit-to-letters map + DFS **Edge Cases to Consider:** - (1) Empty string input - (2) Single digit - (3) Digit "1" (no mapping)

Examples

Example 1

Input: "23"

Output: ["ad","ae","af","bd","be","bf","cd","ce","cf"]

Explanation: 9 combinations

Example 2

Input: ""

Output: []

Explanation: Empty

Example 3

Input: "2"

Output: ["a","b","c"]

Explanation: Single digit

Constraints

▪Input arguments are within valid ranges
▪Optimize for execution speed
▪Handle null/empty inputs gracefully

Watch Out For Edge Cases

▪Empty string input
▪Single digit
▪Digit "1" (no mapping)

Frequently Asked At

AmazonGoogleMicrosoftMetaAdobe

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