我如何保证我的魔方置乱算法不会select同一个方向连续两次？

Question

我正在开发魔方计时器网站，(JavaScript)，它需要一个加扰算法。如果它只是从数组中随机选择字母，那会很容易，但它需要满足一些要求。每个字母代表魔方算法符号中的一个移动，因此例如 "L" 表示顺时针移动左侧。或者 "U2" 表示将 Upper side 移动两次，而“ B' ”表示将 Backside 逆时针移动。等等。

问题是两个相同的字母不能相邻，即使它们在不同的方向也是如此。例如，U 不能紧挨着 U'，或 U2 等等。它必须是不同的字母。有时，我的代码会生成 2 个彼此相邻的相同字母。

这是我的代码：

function generateScramble() {

    //Possible Letters
    var array = new Array(" U", " D", " R", " L", " F", " B", " U\'", " D\'", " R\'", " L\'", " F\'", " B\'", " U2", " D2", " R2", " L2", " F2", " B2"); 

    var array2 = new Array(); // The Scramble.

    var rdArr = new Array(); // The Array of random numbers.

    for (var i = 0; i < 20; i++) {
        var random = Math.floor(Math.random() * array.length);
        rdArr.unshift(random);

        if (rdArr[1] - rdArr[0] == 0 ||
            rdArr[0] - rdArr[1] == 0 ||
            rdArr[1] - rdArr[0] == 6 ||
            rdArr[0] - rdArr[1] == 6 ||
            rdArr[1] - rdArr[0] == 12 ||
            rdArr[0] - rdArr[1] == 12) { // Check whether a D is next to D' or D2, or if F is next to F' or F2, R next to R' or R2, and so on
            if (random < 17) {
                random++;
            } else {
                random--;
            }
        }

        array2.push(array[random]); // Get letters in random order in the array.
    }

    var scramble = "Scramble: " + array2[0] + array2[1] + array2[2] + array2[3] + array2[4]
                                + array2[5] + array2[6] + array2[7] + array2[8] + array2[9]
                                + array2[10] + array2[11] + array2[12] + array2[13] + array2[14]
                                + array2[15] + array2[16] + array2[17] + array2[18] + array2[19];

    document.getElementById("Scramble").innerHTML = scramble; // Display the scramble

}

Answer 1

我想，代码可以这样：

generateScramble();

function generateScramble() {

  // Possible Letters
  var array = new Array(" U", " D", " R", " L", " F", " B")

  // Possible switches
  var switches = ["", "\'", "2"]; 

  var array2 = new Array(); // The Scramble.

  var last = ''; // Last used letter

  var random = 0;

  for (var i = 0; i < 20; i++) {
      // the following loop runs until the last one 
      // letter is another of the new one
      do {
         random = Math.floor(Math.random() * array.length);
      } while (last == array[random]) 

      // assigns the new one as the last one
      last = array[random];

      // the scramble item is the letter
      // with (or without) a switch
      var scrambleItem = array[random] + switches[parseInt(Math.random()*switches.length)];

      array2.push(scrambleItem); // Get letters in random order in the array.
  }

  var scramble = "Scramble: ";
  
  // Appends all scramble items to scramble variable
  for(i=0; i<20; i++) {
     scramble += array2[i];
  }
  
  document.getElementById("Scramble").innerHTML = scramble; // Display the scramble
}

<div id="Scramble"></div>

希望对您有所帮助。

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