// http://codingtra.in

// http://patreon.com/codingtrain

// Code for this video: https://youtu.be/goUlyp4rwiU

​

var vals = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];

​

function setup() {

  createCanvas(400, 300);

}

​

function draw() {

  console.log(vals);

​

  // STEP 1 of the algorithm

  // https://www.quora.com/How-would-you-explain-an-algorithm-that-generates-permutations-using-lexicographic-ordering

  var largestI = -1;

  for (var i = 0; i < vals.length - 1; i++) {

    if (vals[i] < vals[i + 1]) {

      largestI = i;

    }

  }

  if (largestI == -1) {

    noLoop();

    console.log('finished');

  }

​

  // STEP 2

  var largestJ = -1;

  for (var j = 0; j < vals.length; j++) {

    if (vals[largestI] < vals[j]) {

      largestJ = j;

    }

  }

​

  // STEP 3

  swap(vals, largestI, largestJ);

​

  // STEP 4: reverse from largestI + 1 to the end

  var endArray = vals.splice(largestI + 1);

  endArray.reverse();

  vals = vals.concat(endArray);

​

  background(0);

  textSize(64);

  var s = '';

  for (var i = 0; i < vals.length; i++) {

    s += vals[i];

  }

  fill(255);

  text(s, 20, height / 2);

​

​

}

​

function swap(a, i, j) {

  var temp = a[i];

  a[i] = a[j];

  a[j] = temp;

}