Counting Problems and Combinatorics in DSA
Master counting techniques for DSA: permutations, combinations, Pascal's triangle, Catalan numbers, inclusion-exclusion, pigeonhole principle, and modular arithmetic.
·16 min read · #dsa#math#advanced
#math
9 posts · page 1 of 1
Missing Number — Sum and XOR Tricks
Solve the Missing Number problem with three approaches: hashing, Gauss sum formula, and XOR. Includes complexity analysis and interview tips.
·5 min read · #leetcode#arrays#math
Pascal's Triangle — Row-by-Row Construction
Build Pascal's Triangle in O(n^2) time using simple row-by-row addition. Includes a clear diagram, edge cases, and complexity analysis.
·5 min read · #leetcode#arrays#math
Plus One — Carry Propagation Done Right
Add one to a big integer stored as a digit array by walking from the back. Includes carry handling, the all-nines edge case, and complexity analysis.
·4 min read · #leetcode#arrays#math
Palindrome Number — Without Converting to a String
Detect integer palindromes by reversing half the digits with integer math. Learn why string conversion is discouraged and how to handle negatives and trailing zeros.
·6 min read · #dsa#leetcode#math
Unique Paths: Grid DP and Math
Unique Paths in two ways — the O(m * n) grid DP that interviewers expect and the binomial-coefficient closed form that surprises them.
·5 min read · #dsa#leetcode#dp
Math for Coding Interviews: GCD, Primes, Modular Arithmetic
The essential math toolkit for interviews: Euclidean GCD, sieve of Eratosthenes, modular exponentiation, modular inverses, and common pitfalls.
·7 min read · #dsa#math#intermediate
Numbers and Math in JavaScript
A complete beginner's guide to numbers in JavaScript — arithmetic, the Math object, rounding, formatting, NaN, Infinity, and the floating-point quirk every developer must know.
·8 min read · #javascript#beginners#numbers
Numbers and Math in Python
A practical guide to integers, floats, arithmetic operators, operator precedence, the math module, and the floating-point gotchas every Python beginner should know.
·7 min read · #python#beginners#numbers