let rows = 9;           // Number of rows

let w, h;                // Width and height of each square

let symbols = ["☭", "ﷲ", "✄", "✿", "✽", "♡", "ء", "★", "✤"];

let colors = ["#f9ec00", "#f47920", "#e21d3c", "#583f99", "#9a258f", "#17479e", "#00addc", "#ed1846", "#000000"];

let sudokuGrid = [];     // 9x9 grid for Sudoku

​

function setup() {

  createCanvas(450, 450);  // Canvas size

  w = width / cols;        // Width of each square

  h = height / rows;       // Height of each square

  noLoop();                // No continuous drawing

  // Initialize the grid

  generateSolvedSudoku();

  // Create a button to generate a new Sudoku puzzle

  let button = createButton('Generate New Sudoku');

  button.position(10, height + 10);

  button.mousePressed(generateSolvedSudoku);

  drawBackground();

  drawSudoku();

}

​

// Function to draw the background

function drawBackground() {

  let pink = color('#ffaee2');

  let green = color('#b8eea4');

  for (let y = 0; y < rows; y++) {

    for (let x = 0; x < cols; x++) {

      let index = x + (y % 2);

      fill(index % 2 === 0 ? pink : green);

      noStroke(); // Remove strokes from the rectangles

      rect(x * w, y * h, w, h);

    }

  }

}

​

// Function to generate a solved Sudoku puzzle

function generateSolvedSudoku() {

  sudokuGrid = Array.from({ length: 9 }, () => Array(9).fill(0)); // Reset grid

  fillSudoku(0, 0);

}

​

// Function to check if a symbol can be placed

function canPlaceSymbol(row, col, symbol) {

  // Check the row and column

  for (let i = 0; i < 9; i++) {

    if (sudokuGrid[row][i]?.symbol === symbol || sudokuGrid[i][col]?.symbol === symbol) {

      return false;

    }

  }

​

  // Check the 3x3 subgrid

  let startRow = Math.floor(row / 3) * 3;

  let startCol = Math.floor(col / 3) * 3;

​

  for (let i = startRow; i < startRow + 3; i++) {

    for (let j = startCol; j < startCol + 3; j++) {

      if (sudokuGrid[i][j]?.symbol === symbol) {

        return false;

      }

    }

  }

​

  return true;

}

​

// Recursive function to fill the Sudoku grid

function fillSudoku(row, col) {

  if (col === 9) { // Move to the next row

    col = 0;

    row++;

    if (row === 9) return true; // Solved

  }

​

  // Shuffle the symbols and colors to create randomness

  let shuffledIndices = [...Array(symbols.length).keys()];

  shuffledIndices = shuffle(shuffledIndices);

​

  // Try placing each symbol in the current cell

  for (let index of shuffledIndices) {

    let symbol = symbols[index];

    let colorCode = colors[index];

​

    if (canPlaceSymbol(row, col, symbol)) {

      sudokuGrid[row][col] = { symbol, colorCode }; // Place the symbol and color

​

      if (fillSudoku(row, col + 1)) {

        return true; // Continue to next cell

      }

​

      sudokuGrid[row][col] = 0; // Backtrack

    }

  }

​

  return false; // No valid placement found

}

​

// Function to draw the Sudoku grid

function drawSudoku() {

  textSize(90);

  textAlign(CENTER, CENTER);

  for (let row = 0; row < 9; row++) {

    for (let col = 0; col < 9; col++) {

      if (sudokuGrid[row][col] !== 0) {

        fill(sudokuGrid[row][col].colorCode);

        // Draw the symbol centered in a 4x4 block

        text(sudokuGrid[row][col].symbol, col * 4 * w + 2 * w, row * 4 * h + 2 * h);

      }

    }

  }

}

​