Skip to content

Rule of thumb [terminology]

Terminology

Usage

  • n: size of a one-dimensional sequence
  • m, n: matrix row and column counts
  • i, j, k: short-lived generic indices
  • idx: one explicitly named index
  • r, c: row and column coordinates
  • dr, dc: coordinate direction offsets
  • nr, nc: neighboring row and column
  • l, r: moving positional boundaries or pointers
  • lo, hi: lower and upper value bounds
  • start, end: meaningful interval or substring boundaries
  • top, bottom, left, right: four rectangular boundaries
  • mid: midpoint or split position
  • w, r: write and read indices
  • x: generic numeric sequence element
  • val: extracted, stored, or parsed value
  • ch: current or individual character
  • a, b: symmetric arithmetic operands
  • res: constructed return collection
  • ans: generic final scalar answer
  • best: optimum found so far
  • total: additive accumulation
  • cnt: scalar count
  • counts: item-to-count mapping
  • freq: one frequency
  • freqs: frequency mapping
  • acc: general non-specific accumulator
  • profit, gain: domain-specific financial quantities
  • cur, prev, nxt: current, previous, and next state
  • prev1, prev2: one and two positions back
  • node: currently processed node
  • root, head, tail: structural endpoints
  • dummy: sentinel node
  • slow, fast: different-speed pointers
  • q: single compact BFS queue
  • stack, heap: preserve data-structure semantics
  • path: choices in the current backtracking branch
  • front, back: bidirectional search frontiers
  • level: nodes or values at one depth
  • depth: numeric distance from a tree root
  • seen: previously encountered values or states
  • visited: graph or grid elements already traversed
  • used: currently unavailable choices or resources
  • cand: provisional candidate
  • prefix, suffix: directional accumulation around an index
  • rev: reversed representation under construction
  • digit: one numeric digit
  • rem: arithmetic remainder
  • int_part: integer part of a fraction
  • num_str: string representation of a number
  • base: current exponentiation base
  • carry: propagated arithmetic state
  • partial: incomplete intermediate result
  • mask: bitwise mask
  • ordered: sorted or deliberately arranged state
  • width: span or merge-run width
  • size: general element count for a group
  • parts: pieces that will be joined
  • alphabet: complete substitution character set

Why these variable names matter:

  • Interviewers expect them.
  • They compress explanation.
  • They make standard patterns recognizable fast.