JS：重复​​并随机化一个数组X次，以便最后一个索引中的值与上一次迭代中的值不同

Question

我有一个已经随机化并重复X次的数组。如何确保每次迭代时，数组中的最后一项与上一次迭代中的不一样？

function shuffle(array) {
  var currentIndex = array.length, temporaryValue, randomIndex ;

  // While there remain elements to shuffle...
  while (0 !== currentIndex) {

    // Pick a remaining element...
    randomIndex = Math.floor(Math.random() * currentIndex);
    currentIndex -= 1;

    // And swap it with the current element.
    temporaryValue = array[currentIndex];
    array[currentIndex] = array[randomIndex];
    array[randomIndex] = temporaryValue;
  }

  return array;
}

var arr = [1, 2, 3, 4, 5, 6];

for(var i = 0; i < 6; i++) {
    shuffle(arr);
    console.log(arr);
}

示例输出：

[5, 6, 3, 4, 1, 2]
[4, 3, 2, 6, 1, 5]
[6, 1, 3, 4, 5, 2] 
[1, 5, 4, 6, 3, 2] // Last item in array is same as last item in previous array
[6, 3, 5, 4, 2, 1]
[2, 4, 5, 3, 1, 6]

我希望输出的内容：

[5, 6, 3, 4, 1, 2]
[4, 3, 2, 6, 1, 5]
[6, 1, 3, 4, 5, 2]
[1, 5, 2, 6, 3, 4] // Last item in array is different to last item in previous array
[6, 3, 5, 4, 2, 1]
[2, 4, 5, 3, 1, 6]

我猜我需要做一些事情，就像在临时变量中存储前一个和当前数组一样，但到目前为止还没有成功生成正确的逻辑。任何帮助将不胜感激

Answer 1

你可以使用while循环。

while(new_array[new_array.length - 1] == old_array[old_array.length - 1]) {
    // Do some randomising
}

显然，将这​​个随机称为有点延伸。

Answer 2

所以每次遇到问题时都要向左推，这里是一个使用previousLast全局变量的解决方案（也许你应该将所有类都包装在一个更干净的类中）：

var arr = [1, 2, 3, 4, 5, 6];
var previousLast = 0;

for(var i = 0; i < 60; i++) {
    // here you should reassign arr because, if arr is rolled, this is a new array.
    arr = shuffle(arr);
    console.log(arr);
}

function rollLeft(a) {
    var b = [];
    for(var i = 0, n = a.length; i < n; ++i) {
        b.push(a[(i + 1) % n]);
    }
    return b;
}

function shuffle(array) {
  var currentIndex = array.length, temporaryValue, randomIndex ;

  // While there remain elements to shuffle...
  while (0 !== currentIndex) {

    // Pick a remaining element...
    randomIndex = Math.floor(Math.random() * currentIndex);
    currentIndex -= 1;

    // And swap it with the current element.
    temporaryValue = array[currentIndex];
    array[currentIndex] = array[randomIndex];
    array[randomIndex] = temporaryValue;
  }

  if(array[array.length - 1] == previousLast) {
    array = rollLeft(array);
  }

  previousLast = array[array.length - 1];

  return array;
}