sudoku-solver.md

id	title	challengeType	forumTopicId	dashedName
5e601bf95ac9d0ecd8b94afd	Sudoku Solver	4	462357	sudoku-solver

--description--

Build a full stack JavaScript app that is functionally similar to this: https://sudoku-solver.freecodecamp.rocks/. Working on this project will involve you writing your code using one of the following methods:

• Clone this GitHub repo and complete your project locally.
• Use our Gitpod starter project to complete your project.
• Use a site builder of your choice to complete the project. Be sure to incorporate all the files from our GitHub repo.

--instructions--

• All puzzle logic can go into /controllers/sudoku-solver.js
  • The validate function should take a given puzzle string and check it to see if it has 81 valid characters for the input.
  • The check functions should be validating against the current state of the board.
  • The solve function should handle solving any given valid puzzle string, not just the test inputs and solutions. You are expected to write out the logic to solve this.
• All routing logic can go into /routes/api.js
• See the puzzle-strings.js file in /controllers for some sample puzzles your application should solve
• To run the challenge tests on this page, set NODE_ENV to test without quotes in the .env file
• To run the tests in the console, use the command npm run test.

Write the following tests in tests/1_unit-tests.js:

• Logic handles a valid puzzle string of 81 characters
• Logic handles a puzzle string with invalid characters (not 1-9 or .)
• Logic handles a puzzle string that is not 81 characters in length
• Logic handles a valid row placement
• Logic handles an invalid row placement
• Logic handles a valid column placement
• Logic handles an invalid column placement
• Logic handles a valid region (3x3 grid) placement
• Logic handles an invalid region (3x3 grid) placement
• Valid puzzle strings pass the solver
• Invalid puzzle strings fail the solver
• Solver returns the expected solution for an incomplete puzzle

Write the following tests in tests/2_functional-tests.js

• Solve a puzzle with valid puzzle string: POST request to /api/solve
• Solve a puzzle with missing puzzle string: POST request to /api/solve
• Solve a puzzle with invalid characters: POST request to /api/solve
• Solve a puzzle with incorrect length: POST request to /api/solve
• Solve a puzzle that cannot be solved: POST request to /api/solve
• Check a puzzle placement with all fields: POST request to /api/check
• Check a puzzle placement with single placement conflict: POST request to /api/check
• Check a puzzle placement with multiple placement conflicts: POST request to /api/check
• Check a puzzle placement with all placement conflicts: POST request to /api/check
• Check a puzzle placement with missing required fields: POST request to /api/check
• Check a puzzle placement with invalid characters: POST request to /api/check
• Check a puzzle placement with incorrect length: POST request to /api/check
• Check a puzzle placement with invalid placement coordinate: POST request to /api/check
• Check a puzzle placement with invalid placement value: POST request to /api/check

--hints--

You should provide your own project, not the example URL.

(getUserInput) => {
  const url = getUserInput('url');
  assert(!/.*\/sudoku-solver\.freecodecamp\.rocks/.test(getUserInput('url')));
};

You can POST /api/solve with form data containing puzzle which will be a string containing a combination of numbers (1-9) and periods . to represent empty spaces. The returned object will contain a solution property with the solved puzzle.

async (getUserInput) => {
  const input =
    '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..';
  const output =
    '769235418851496372432178956174569283395842761628713549283657194516924837947381625';
  const data = await fetch(getUserInput('url') + '/api/solve', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ puzzle: input })
  });
  const parsed = await data.json();
  assert.property(parsed, 'solution');
  assert.equal(parsed.solution, output);
};

If the object submitted to /api/solve is missing puzzle, the returned value will be { error: 'Required field missing' }

async (getUserInput) => {
  const input =
    '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..';
  const output = 'Required field missing';
  const data = await fetch(getUserInput('url') + '/api/solve', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ notpuzzle: input })
  });
  const parsed = await data.json();
  assert.property(parsed, 'error');
  assert.equal(parsed.error, output);
};

If the puzzle submitted to /api/solve contains values which are not numbers or periods, the returned value will be { error: 'Invalid characters in puzzle' }

async (getUserInput) => {
  const input =
    'AA9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..';
  const output = 'Invalid characters in puzzle';
  const data = await fetch(getUserInput('url') + '/api/solve', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ puzzle: input })
  });
  const parsed = await data.json();
  assert.property(parsed, 'error');
  assert.equal(parsed.error, output);
};

If the puzzle submitted to /api/solve is greater or less than 81 characters, the returned value will be { error: 'Expected puzzle to be 81 characters long' }

async (getUserInput) => {
  const inputs = [
    '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6.',
    '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6...'
  ];
  const output = 'Expected puzzle to be 81 characters long';
  for (const input of inputs) {
    const data = await fetch(getUserInput('url') + '/api/solve', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ puzzle: input })
    });
    const parsed = await data.json();
    assert.property(parsed, 'error');
    assert.equal(parsed.error, output);
  }
};

If the puzzle submitted to /api/solve is invalid or cannot be solved, the returned value will be { error: 'Puzzle cannot be solved' }

async (getUserInput) => {
  const input =
    '9.9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..';
  const output = 'Puzzle cannot be solved';
  const data = await fetch(getUserInput('url') + '/api/solve', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ puzzle: input })
  });
  const parsed = await data.json();
  assert.property(parsed, 'error');
  assert.equal(parsed.error, output);
};

You can POST to /api/check an object containing puzzle, coordinate, and value where the coordinate is the letter A-I indicating the row, followed by a number 1-9 indicating the column, and value is a number from 1-9.

async (getUserInput) => {
  const input =
    '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..';
  const coordinate = 'A1';
  const value = '7';
  const data = await fetch(getUserInput('url') + '/api/check', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ puzzle: input, coordinate, value })
  });
  const parsed = await data.json();
  assert.property(parsed, 'valid');
  assert.isTrue(parsed.valid);
};

The return value from the POST to /api/check will be an object containing a valid property, which is true if the number may be placed at the provided coordinate and false if the number may not. If false, the returned object will also contain a conflict property which is an array containing the strings "row", "column", and/or "region" depending on which makes the placement invalid.

async (getUserInput) => {
  const input =
    '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..';
  const coordinate = 'A1';
  const value = '1';
  const conflict = ['row', 'column'];
  const data = await fetch(getUserInput('url') + '/api/check', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ puzzle: input, coordinate, value })
  });
  const parsed = await data.json();
  assert.property(parsed, 'valid');
  assert.isFalse(parsed.valid);
  assert.property(parsed, 'conflict');
  assert.include(parsed.conflict, 'row');
  assert.include(parsed.conflict, 'column');
};

If value submitted to /api/check is already placed in puzzle on that coordinate, the returned value will be an object containing a valid property with true if value is not conflicting.

async (getUserInput) => {
  const input =
  '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..';
  const coordinate = 'C3';
  const value = '2';
  const data = await fetch(getUserInput('url') + '/api/check', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ puzzle: input, coordinate, value })
  });
  const parsed = await data.json();
  assert.property(parsed, 'valid');
  assert.isTrue(parsed.valid);
};

If the puzzle submitted to /api/check contains values which are not numbers or periods, the returned value will be { error: 'Invalid characters in puzzle' }

async (getUserInput) => {
  const input =
    'AA9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..';
  const coordinate = 'A1';
  const value = '1';
  const output = 'Invalid characters in puzzle';
  const data = await fetch(getUserInput('url') + '/api/check', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ puzzle: input, coordinate, value })
  });
  const parsed = await data.json();
  assert.property(parsed, 'error');
  assert.equal(parsed.error, output);
};

If the puzzle submitted to /api/check is greater or less than 81 characters, the returned value will be { error: 'Expected puzzle to be 81 characters long' }

async (getUserInput) => {
  const inputs = [
    '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6.',
    '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6...'
  ];
  const coordinate = 'A1';
  const value = '1';
  const output = 'Expected puzzle to be 81 characters long';
  for (const input of inputs) {
    const data = await fetch(getUserInput('url') + '/api/check', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ puzzle: input, coordinate, value })
    });
    const parsed = await data.json();
    assert.property(parsed, 'error');
    assert.equal(parsed.error, output);
  }
};

If the object submitted to /api/check is missing puzzle, coordinate or value, the returned value will be { error: 'Required field(s) missing' }

async (getUserInput) => {
  const inputs = [
    {
      puzzle: '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..',
      value: '1',
    },
    {
      puzzle: '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..',
      coordinate: 'A1',
    },
    {
      coordinate: 'A1',
      value: '1'
    }
  ];
  for (const input of inputs) {
    const output = 'Required field(s) missing';
    const data = await fetch(getUserInput('url') + '/api/check', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(input)
    });
    const parsed = await data.json();
    assert.property(parsed, 'error');
    assert.equal(parsed.error, output);
  }
};

If the coordinate submitted to api/check does not point to an existing grid cell, the returned value will be { error: 'Invalid coordinate'}

async (getUserInput) => {
  const input =
    '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..';
  const output = 'Invalid coordinate';
  const coordinates = ['A0', 'A10', 'J1', 'A', '1', 'XZ18'];
  const value = '7';
  for (const coordinate of coordinates) {
    const data = await fetch(getUserInput('url') + '/api/check', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ puzzle: input, coordinate, value })
    });
    const parsed = await data.json();
    assert.property(parsed, 'error');
    assert.equal(parsed.error, output);
  }
};

If the value submitted to /api/check is not a number between 1 and 9, the returned value will be { error: 'Invalid value' }

async (getUserInput) => {
  const input =
    '..9..5.1.85.4....2432......1...69.83.9.....6.62.71...9......1945....4.37.4.3..6..';
  const output = 'Invalid value';
  const coordinate = 'A1';
  const values = ['0', '10', 'A'];
  for (const value of values) {
    const data = await fetch(getUserInput('url') + '/api/check', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ puzzle: input, coordinate, value })
    });
    const parsed = await data.json();
    assert.property(parsed, 'error');
    assert.equal(parsed.error, output);
  }
};

All 12 unit tests are complete and passing.

async (getUserInput) => {
  try {
    const getTests = await $.get(getUserInput('url') + '/_api/get-tests');
    assert.isArray(getTests);
    const unitTests = getTests.filter((test) => {
      return !!test.context.match(/Unit\s*Tests/gi);
    });
    assert.isAtLeast(unitTests.length, 12, 'At least 12 tests passed');
    unitTests.forEach((test) => {
      assert.equal(test.state, 'passed', 'Test in Passed State');
      assert.isAtLeast(
        test.assertions.length,
        1,
        'At least one assertion per test'
      );
    });
  } catch (err) {
    throw new Error(err.responseText || err.message);
  }
};

All 14 functional tests are complete and passing.

async (getUserInput) => {
  try {
    const getTests = await $.get(getUserInput('url') + '/_api/get-tests');
    assert.isArray(getTests);
    const functTests = getTests.filter((test) => {
      return !!test.context.match(/Functional\s*Tests/gi);
    });
    assert.isAtLeast(functTests.length, 14, 'At least 14 tests passed');
    functTests.forEach((test) => {
      assert.equal(test.state, 'passed', 'Test in Passed State');
      assert.isAtLeast(
        test.assertions.length,
        1,
        'At least one assertion per test'
      );
    });
  } catch (err) {
    throw new Error(err.responseText || err.message);
  }
};

--solutions--

/**
  Backend challenges don't need solutions,
  because they would need to be tested against a full working project.
  Please check our contributing guidelines to learn more.
*/