Eric's Space

Problem LinkLeetCode 1582 - Special Positions in a Binary Matrix Difficulty: EasyTopic: Array, Hash Table, MatrixDaily Question: 4th March 2026 Problem RecapGiven an m x n binary matrix mat where each element is either 0 or 1, return the number of special positions in the matrix. A position (i, j) is called special if: mat[i][j] == 1 All other elements in row i are 0 All other elements in column j are 0 Constraints: 1 <= m, n <= 100 mat[i][j] is either 0 or 1 Examples: mat = [[1,0...

Problem LinkLeetCode 166 - Fraction to Recurring Decimal Difficulty: MediumTopic: Hash Table, Math, StringDaily Question: 24th September 2025 Problem RecapGiven two integers representing the numerator and denominator of a fraction, we need to return the fraction in string format. The key challenge is handling recurring decimal patterns properly. Requirements: If the fractional part repeats, enclose the repeating part in parentheses Handle negative signs correctly (only when numerator and de...

Problem LinkLeetCode 966 - Vowel Spellchecker Difficulty: MediumTopic: String, Hash TableDaily Question: 14th September 2025 Problem RecapWe need to implement a spellchecker that corrects query words based on a given wordlist. The spellchecker handles two types of spelling mistakes with specific precedence rules: Capitalization errors: Case-insensitive matching Vowel errors: Vowels (‘a’, ‘e’, ‘i’, ‘o’, ‘u’) can be interchanged Precedence Rules (in order): Exact match (case-sensitive) → re...

Problem LinkLeetCode 3227 - Vowels Game in a String Difficulty: MediumTopic: Game Theory, StringDaily Question: 12th September 2025 Problem RecapWe are given a string s. Two players, Alice and Bob, take turns deleting substrings under these rules: Alice’s move: she must delete a non-empty substring that contains an odd number of vowels. Odd numbers are: 1, 3, 5, 7, … For example, substrings like "a" (1 vowel), "iou" (3 vowels), "banana" (3 vowels). Bob’s move...

Problem LinkLeetCode 1317 - Convert Integer to the Sum of Two No-Zero Integers Difficulty: EasyTopic: Array, MathDaily Question: 8th September 2025 Video Explanation Watch the complete solution walkthrough on my YouTube channel! IntuitionWe need two positive integers a and b such that a + b = n and neither a nor b contains the digit 0 anywhere in its decimal representation. Important clarification: “No-Zero integer” does not mean “the number is not equal to 0”; it means no digit '0...

Problem LinkLeetCode 1304 - Find N Unique Integers Sum up to Zero Difficulty: EasyTopic: Array, MathDaily Question: 7th September 2025 Video Explanation Watch the complete solution walkthrough on my YouTube channel! IntuitionWhen we want n unique integers that sum to zero, the first idea is symmetry.Pairs like (x, -x) cancel each other out perfectly. So the solution is to build the array from opposite pairs, and if needed, include 0 as a neutral element. Approach If n is even: take n // 2 ...