为什么这个函数不返回给定数组的所有排列工作？

Question

我正在尝试编写一个函数，该函数将返回给定数字数组的所有排列，如下例所示：

a = [1, 1, 2]
permutator(a) = [
  [1,1,2],
  [1,2,1],
  [2,1,1]
]

b = [2, 3, 4]
permutator(b) = [
  [2,3,4],
  [2,4,3],
  [3,2,4],
  [3,4,2],
  [4,2,3],
  [4,3,2]
]

结果顺序不正确

您能否解释为什么下面的代码不起作用？我尝试调试，但我认为变量[[temp和结果没有作为数组保留在内存中，但我不确定是否是这种情况，也不确定如何解决它。

permutator = (array) => {
  const result = [];

  array.forEach((num, i) => {
    array.forEach((num2, j) => {
      if (i !== j) {
        let temp = array;
        temp[i] = temp[j];
        temp[j] = num;
        console.log(`temp: ${temp}`);
        console.log(`result: ${result}`);
        if (!result.includes(temp)) result.push(temp);
        console.log(`result: ${result}`);
      }
    });
  });

  return result;
}

您可以看到我尝试了console.loging一切都没有用...

Answer 1

这适用于三位数，但我不会称呼它为优雅：

let indexAtEachPosition = function (ind, arr) {
  let arrayGroup = [];
  let arrLength = arr.length;
  let movedArray = [...arr];
  for (let indx = 0; indx < arrLength; indx++) {
    let firstItem = movedArray[0];
    let otherItems = movedArray.slice(1);
    otherItems[arrLength - 1] = firstItem
    movedArray = [...otherItems];
    arrayGroup.push(movedArray.join(" "));
  }
  return arrayGroup;
}

let permutator = function permutator(values) {
  let returnValue = new Set();
  let digitCount = values.length;
  returnValue.add(values.join(" "));

  values.forEach(digit => {
    indexAtEachPosition(digit, values).forEach(variation => {
      returnValue.add(variation);
    });
  });
  [...values.reverse()].forEach(digit => {
    indexAtEachPosition(digit, values).forEach(variation => {
      returnValue.add(variation);
    });
  });
  return [...returnValue].map(eachArr => {
    return eachArr.split(" ");
  });
};



// console.log( permutator([0,0,0]) );
// console.log( permutator([1,0,0]) );
// console.log( permutator([1,2,3]) );
console.log( permutator([1,1,2]) );
console.log( permutator([2,3,4]) );