Rust practice in Systems Programming

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• The Classic Chant

  The interview warm-up that never dies. Return Fizz, Buzz, FizzBuzz, or the number, with match-free if/else.

  control. Free room.

• Your First Borrow

  Borrow a slice, do not own it. Sum its elements and hand the answer back; the caller keeps the data.

  borrow. Free room.

• Leap of Faith

  Calendars hide a tidy rule. Decide whether a year is a leap year: divisible by 4, not 100, unless also by 400.

  logic. Free room.

• Warm the Core

  Every Rust program is a set of typed functions. Double a number and return it, the smallest possible expression.

  bindings. Free room.

• Count the Words

  Split on whitespace, collapsing runs of spaces, and count the words.

  strings. Account access required.

• Find the Peak

  Scan a borrowed slice and report its largest value, reading through a shared reference.

  borrow. Account access required.

• Tally the Letter

  Walk the characters of a string and count how often one appears, all through a borrow.

  strings. Account access required.

• Turn It Around

  Reverse a string by characters, collecting them into a fresh owned String.

  strings. Account access required.

• Are They Anagrams?

  Two words are anagrams when their sorted characters match. Decide it.

  sets. Account access required.

• Fail With a Reason

  Return a Result with a clear error for a zero divisor or an unrepresentable signed quotient; otherwise return Ok of the integer quotient.

  result. Account access required.

• Grade the Paper

  Use range patterns in a match to turn a score into a letter grade.

  match. Account access required.

• Never Divide by Zero

  Represent a missing quotient with Option. Return None for a zero divisor or an unrepresentable signed quotient; otherwise return Some of the integer quotient.

  option. Account access required.

• How Many Distinct?

  Drop duplicates with a HashSet and count what is left.

  sets. Account access required.

• Keep a Running Total

  Use scan to carry state through an iterator and emit the cumulative sums.

  advanced. Account access required.

• One Function, All Types

  Write it once over a generic T with a bound, and return whichever argument is larger.

  generics. Account access required.

• A One-Line Pipeline

  Compose filter, map, and sum into a single expression: the sum of the squares of the even numbers.

  adapters. Account access required.

• Share the Counter

  Add each element to a shared Arc<Mutex> from its own thread, then join all and read the total.

  shared. Account access required.

• Ship the Engine

  Run a tiny program of SET/GET/INCR commands against a HashMap store and count the outputs.

  engine. Account access required.

• Sum on a Thread

  Move an owned vector onto a spawned thread, reduce it there, and join the result back.

  threads. Account access required.

• The Pocket Calculator

  Evaluate a reverse-Polish expression on a stack, returning Ok or an Err for bad input.

  eval. Account access required.