arrrepeat/lib/arrRepeat.js

传入一个数或多个返回有多少种排序方式和结果

class ArrRepeat {
    constructor(num) {
        this._arr = (String(num)).split('');
        this.init();
    }
    init() {
        this._arr = this.endArr(this.perm(this._arr))
    }
    perm(arr) {
        let newArr = [];
        (function fn(source, res) {
            if (source.length == 0) {
                newArr.push(res);
            } else {
                source.forEach((item, index) => {
                    fn(source.slice(0, index).concat(source.slice(index + 1)), res.concat(source[index]));
                })
            }
        })(arr, []);
        return newArr;
    }
    endArr(arr) {
        let result = [];
        let hash = {};
        arr.forEach((item, index) => {
            if (!hash[item]) {
                result.push(item);
                hash[item] = true;
            }
        })
        return result
    }
}

module.exports = function(num) {
    return new ArrRepeat(num)._arr;
}

// var num = 131419;
// arrRepeat(num).forEach(function (item, index) {
//     console.log(`第${index + 1}种情况，结果为${item}`)
// })