Problem 01

Readability 2.0

Coleman–Liau Grade Level Calculator

Upload your .java file. Your program must:

  • Read one line of text from stdin with Scanner.nextLine()
  • Print exactly one line: Grade X, Before Grade 1, or Grade 16+
Problem 02

Credit Card Validator

Luhn's Algorithm + Card Type Detection

Upload your .java file. Your program must:

  • Read a card number string from stdin with Scanner.next()
  • Print one word: VISA, AMEX, MASTERCARD, VALID, or INVALID
  • Reject non-digit characters without running Luhn's
Problem 03

Cipher Cracker

Frequency Analysis + Hill Climbing

Upload your .java file. Your program must:

  • Read one line of ciphertext from stdin with Scanner.nextLine()
  • Print a mapping table headed by Mapping:
  • Print the decoded text headed by Decoded:

⚠️ Scoring is approximate — hill climbing is randomized. The grader checks output format and that ≥ 5 common English dictionary words appear in the decoded text.

Problem 04

Recover

Hidden Message in 2D Intensity Grid

Upload your .java file. Your program must:

  • Hard-code the 5×10 "AB" sample grid from the problem spec
  • Take no input — run without reading stdin
  • Print the decoded message on one line (expected: AB)

💡 Make sure to use the exact sample grid from the problem. The grader checks that your output contains AB.

Problem 05

DNA Matching

STR Longest-Run Analysis

Upload your .java file. Your program must:

  • Read one DNA sequence from stdin with Scanner.nextLine()
  • Compute the longest run of each STR: AGATC, TTTTTTCT, AATG, TCTAG
  • Print the matching person's name, or No match
Problem 06

Runoff

Ranked-Choice Election Simulator

Upload your .java file. Your program must:

  • Read number of candidates, then each name, then number of voters, then each voter's ranking (space-separated names)
  • Simulate rounds of elimination until one candidate has a majority or all remaining are tied
  • Print the winner's name, or all tied names (one per line)
Problem 07

Speller Lite

Binary Search Spell Checker (No HashSet)

Upload your .java file. Your program must:

  • Read one line of text from stdin with Scanner.nextLine()
  • Normalize each word (lowercase, strip surrounding punctuation)
  • Print MISSPELLED WORDS, then each misspelled word (alphabetically, no duplicates)
  • Print WORDS IN TEXT: and MISSPELLINGS: summary lines
Problem 08

Minesweeper

Clue Generator + Connected Zero Regions

Upload your .java file. Your program must:

  • Hard-code the 4×4 Sample 1 board: mines at (0,2) and (2,1)
  • Take no input — run without reading stdin
  • Print the clue grid with each cell space-separated (e.g. 1 1 * 1)

💡 The grader checks that all four rows of the clue grid appear in your output: 1 1 * 1   1 2 2 1   1 * 2 0   1 1 2 0