创建循环以检查排列中的循环

Question

我的作业分配让我检查用户输入的数字中所有可能的周期符号。 我已经将输入发送到数组中，但是我不确定如何开始循环。 如何编辑此循环以使相同的数字显示不超过一次？ 抱歉，如果格式不正确，请首次发布。

// example of user input
var permutation = [ 9,2,3,7,4,1,8,6,5 ] ;   

// add zero to match index with numbers
permutation.unshift(0) ;

// loop to check for all possible permutations
for (var i = 1; i < permutation.length -1; i++)
{
    var cycle = [];
    var currentIndex = i ;
    if ( permutation [ currentIndex ] == i )
        cycle.push(permutation [currentIndex]);
    while ( permutation [ currentIndex ] !== i )
    {
        cycle.push( permutation [currentIndex]);
        currentIndex = permutation [ currentIndex ] ;
    }

    // display in console
    console.log(cycle);
}

Answer 1

我在这里回答了类似的问题。 这个想法是使用递归函数。
这是一个示例：

 var array = ['a', 'b', 'c']; var counter = 0; //This is to count the number of arrangement possibilities permutation(); console.log('Possible arrangements: ' + counter); //Prints the number of possibilities function permutation(startWith){ startWith = startWith || ''; for (let i = 0; i < array.length; i++){ //If the current character is not used in 'startWith' if (startWith.search(array[i]) == -1){ //If this is one of the arrangement posibilities if ((startWith + array[i]).length == array.length){ counter++; console.log(startWith + array[i]); //Prints the string in console } //If the console gives you "Maximum call stack size exceeded" error //use 'asyncPermutation' instead //but it might not give you the desire output //asyncPermutation(startWith + array[i]); permutation(startWith + array[i]); //Runs the same function again } else { continue; //Skip every line of codes below and continue with the next iteration } } function asyncPermutation(input){ setTimeout(function(){permutation(input);},0); } }