[5, 3, 0, 0, 7, 0, 0, 0, 0],

  [6, 0, 0, 1, 9, 5, 0, 0, 0],

  [0, 9, 8, 0, 0, 0, 0, 6, 0],

  [8, 0, 0, 0, 6, 0, 0, 0, 3],

  [4, 0, 0, 8, 0, 3, 0, 0, 1],

  [7, 0, 0, 0, 2, 0, 0, 0, 6],

  [0, 6, 0, 0, 0, 0, 2, 8, 0],

  [0, 0, 0, 4, 1, 9, 0, 0, 5],

  [0, 0, 0, 0, 8, 0, 0, 7, 9]

]

​

function setup() {

  createCanvas(400, 400);

  solve();

}

​

function draw() {

  background(255);

  // solve();

  drawSudoku(grid);

​

}

​

function drawSudoku(grid) {

  strokeWeight(2);

  line(width / 3, 0, width / 3, height);

  line(width * 2 / 3, 0, width * 2 / 3, height);

  line(0, height / 3, width, height / 3);

  line(0, height * 2 / 3, width, height * 2 / 3);

  strokeWeight(1);

  for (let i = 0; i < 9; i++) {

    line(i * width / 9, 0, i * width / 9, height);

    line(0, i * height / 9, width, i * height / 9);

  }

  textAlign(CENTER, CENTER);

  textSize(28);

  for (let r in grid) {

    row = grid[r];

    for (let c in row) {

      cell = row[c];

      if (cell !== 0) {

        text(cell, c * width / 9 + width / 18, r * height / 9 + width / 18);

      }

    }

  }

}

​

function possible(x, y, n) {

  for (let i = 0; i < 9; i++) {

    if (grid[y][i] == n) return false

    if (grid[i][x] == n) return false

  }

  let x0 = floor(x / 3) * 3

  let y0 = floor(y / 3) * 3

  for (let i = 0; i < 3; i++) {

    for (let i = 0; i < 3; i++) {

      if (grid[y0 + i][x0 + i] == n) return false

    }

  }

  return true;

}

​

function solve() {

  let find = findEmpty();

  let x, y;

  if (!find[0]) return true;

  else {

      x = find[0];

      y = find[1];

  }

  for (i = 1; i < 10; i++) {

    if (possible(x, y, i)) {

      grid[y][x] = i;

      if(solve()) return true;

      grid[y][x] = 0;

    }

  }

  return false;

}

​

function findEmpty() {

  for (let y = 0; y < 9; y++) {

    for (let x = 0; x < 9; x++) {

      if(grid[y][x]==0){

        return [x, y];

      }

    }

  }

  return null;

}