Handle palindrome & decimal addition
Company: Meta
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: Medium
Interview Round: Technical Screen
##### Question
LeetCode 266. Palindrome Permutation Given two non-negative decimal number strings, implement addition that supports a decimal point.
https://leetcode.com/problems/palindrome-permutation/description/
Quick Answer: This question evaluates string manipulation and numeric representation skills, specifically handling decimal-point addition with arbitrary precision and reasoning about palindrome/permutation properties.
Given two non-negative decimal number strings a and b, return their sum as a normalized decimal string. The strings may contain at most one decimal point. Perform digit-wise addition; do not parse the entire strings as numeric types. Normalization rules for the output: remove leading zeros in the integer part (but keep a single '0' if the number is zero), remove trailing zeros in the fractional part, and omit the decimal point if the fractional part becomes empty.
Constraints
- 1 <= len(a), len(b) <= 100000
- a and b contain only digits and at most one '.'
- If '.' is present, there is at least one digit on both sides (matches regex: ^[0-9]+(\.[0-9]+)?$)
- No signs, spaces, or exponent notation
- Must not convert the entire strings to integers/floats/decimals; use digit-wise addition
- Return must be normalized as described
Examples
Input:
Expected Output: 13
Input:
Expected Output: 1000
Input:
Expected Output: 16
Input:
Expected Output: 0
Input:
Expected Output: 579.789
Input:
Expected Output: 0
Input:
Expected Output: 1.24
Input:
Expected Output: 1000
Hints
- Split each input around the decimal point into integer and fractional parts.
- Pad the shorter fractional part with trailing zeros so both fractions have equal length.
- Add fractional parts right-to-left, carrying into the integer part if needed.
- Add integer parts right-to-left, including any carry from the fractional sum.
- Trim trailing zeros from the fractional result and leading zeros from the integer result; remove the decimal point if the fractional part becomes empty.