let walls = {};

​

let visited = {};

let q = [];

​

let val = 0;

​

let gridSize = 20;

​

const DFS = "DFS";

const BFS = "BFS";

​

let searchMode = BFS;

​

const WALL = "WALL";

const SRCH = "SRCH";

​

let drawMode = SRCH;

​

function setup() {

  createCanvas(400, 400);

  colorMode(HSB, 255);

}

​

function draw() {

  background(220);

  drawGrid();

  if(q.length) {

    let curr;

    if(searchMode === DFS) {

      curr = q.pop();

    } else if(searchMode === BFS) {

      curr = q.shift();

    }

    let pos = curr.split(":");

    let x = parseInt(pos[0]) | 0;

    let y = parseInt(pos[1]) | 0;

    let n = neighbours(x, y);

    for(let i = 0; i < n.length; i ++) {

      if(!(n[i] in visited)) {

        q.push(n[i]);

        visited[n[i]] = val;

        val = (val + 1) % 256;

      }

    }

  }

  fill(0);

  text(searchMode, 10, 10);

  text(drawMode, 10, 20);

}

​

function test() {

  for(let i = 0; i < width; i ++) {

    stroke(i % 256, 255, 255);

    line(i, 0, i, height);

  }

}

​

function neighbours(x, y) {

  let n = [];

  for(let i = -1; i <= 1; i ++) {

    for(let j = -1; j <= 1; j ++) {

      if(i === 0 && j === 0) {

        continue;

      }

      let nx = (x + i) | 0;

      let ny = (y + j) | 0;

      let k = nx + ":" + ny;

      if(inBounds(nx, ny) && !(k in walls)) {

        n.push(k);

      }

    }

  }

  return n;

}

​

function inBounds(x, y) {

  return x >= 0 && x < width/gridSize &&

        y >= 0 && y < height/gridSize;

}

​

function keyTyped() {

  if(key === "b") {

    searchMode = BFS;

  } else if(key === "d") {

    searchMode = DFS;

  } else if(key === "w") {

    drawMode = WALL;

  } else if(key === "s") {

    drawMode = SRCH;

  }

}

​

function mouseReleased() {

  let x = (mouseX/gridSize) | 0;

  let y = (mouseY/gridSize) | 0;

  let k = x + ":" + y;

  if(drawMode === SRCH) {

    visited = {};

​

    q = [k];

    visited[k] = 0;

    val = 1;

  } else if(drawMode === WALL) {

    if(k in walls) {

      delete walls[k];

    } else {

      walls[k] = true;

    }

  }

}

​

function drawGrid() {

  for(let j = 0; j < height/gridSize; j ++) {

    for(let i = 0; i < width/gridSize; i ++) {

      let k = i+":"+j;

      if(k in walls) {

        fill(0);

      } else if(k in visited) {

        fill(visited[k], 255, 255);

      } else {

        fill(0, 0, 255);

      }

      rect(i * gridSize, j * gridSize, gridSize, gridSize);

    }  

  }

}