bertoort / sugoku

Sudoku puzzle solver and generator

suGOku

https://sugoku.onrender.com/

Go Challenge 8 solution for the month of November 2015.

*The API is hosted on a Render free tier instance. The server gets spun down with inactivity, expect a delay of 50 secs or more for the initial request. Then it's ⚡

Overview

Sudoku web app: solves, generates, grades, and validates sudoku puzzles.

The algorithm implements two solving functions:

1. QuickFill - Called so because it quickly checks horizontally, vertically and in the nine grid box for possible options. If only one possible solution remains, it adds the value to the square.

2. Guess - It fills an empty square with a possible, non-conflicting value. If the puzzle is solved (completely filled), it validates to see if it correct. If not, it goes back and fills the square with another possible value. It recursively fills in and backtracks until the puzzle is complete.

A very interesting finding was that implementing the QuickFill function before each guess did not improve the speed of the algorithm, in fact, it slowed it down. I was not expecting it. I was so surprised that I decided to keep the original name I had given the function without Quickfill: SlowSolve().

SlowSolve is the faster function and therefore the one used for the API.

Installation

go get github.com/bertoort/sugoku

Technologies

• Go
• Gin
• Semantic UI
• jQuery
• Render
• Godep

API

Get

Board - returns a puzzle board

https://sugoku.onrender.com/board

Arguments -

• Difficulty:
  • easy
  • medium
  • hard
  • random

Example:

https://sugoku.onrender.com/board?difficulty=easy

Post

Solve - returns the solved puzzle, along with difficulty and status

https://sugoku.onrender.com/solve

Grade - returns the difficulty of the puzzle

https://sugoku.onrender.com/grade

Validate - returns the status of the puzzle

https://sugoku.onrender.com/validate

NOTE:

The request does not support content-type of application/json. It must be application/x-www-form-urlencoded

To help, here is a quick and dirty encoding functions for a board:

const encodeBoard = (board) => board.reduce((result, row, i) => result + `%5B${encodeURIComponent(row)}%5D${i === board.length -1 ? '' : '%2C'}`, '')

const encodeParams = (params) =>
  Object.keys(params)
  .map(key => key + '=' + `%5B${encodeBoard(params[key])}%5D`)
  .join('&');

Here is an example sending a board:

const data = {board:[[0,0,0,0,0,0,8,0,0],[0,0,4,0,0,8,0,0,9],[0,7,0,0,0,0,0,0,5],[0,1,0,0,7,5,0,0,8],[0,5,6,0,9,1,3,0,0],[7,8,0,0,0,0,0,0,0],[0,2,0,0,0,0,0,0,0],[0,0,0,9,3,0,0,1,0],[0,0,5,7,0,0,4,0,3]]}

fetch('https://sugoku.onrender.com/solve', {
  method: 'POST',
  body: encodeParams(data),
  headers: { 'Content-Type': 'application/x-www-form-urlencoded' }
})
  .then(response => response.json())
  .then(response => console.log(response.solution))
  .catch(console.warn)

jQuery Example:

var data = {
  board: "[[0,0,1,0,0,0,0,0,0],
          [2,0,0,0,0,0,0,7,0],
          [0,7,0,0,0,0,0,0,0],
          [1,0,0,4,0,6,0,0,7],
          [0,0,0,0,0,0,0,0,0],
          [0,0,0,0,1,2,5,4,6],
          [3,0,2,7,6,0,9,8,0],
          [0,6,4,9,0,3,0,0,1],
          [9,8,0,5,2,1,0,6,0]]"
}
$.post('https://sugoku.onrender.com/solve', data)
  .done(function (response) {

    <% response = {
      difficulty: "hard",
      solution: Array[9],
      status: "solved"
    } &>

  });```

For more, check out the [api.js](https://github.com/bertoort/sugoku/blob/master/public/api.js) file

sugoku's Issues

Service unhealthy

cant use api please check the link

Not true sudokus

The generation algorithm you are using isn't making true sudokus, after solving multiple puzzles I noticed that you can solve a couple of them in different ways, meaning they don't have unique solution which is a requirement of true sudokus. I love the API and was using it to make my own sudoku implementation as a challenge to myself, but till this produces true sudokus. I'll have to look to other web apis.