javascript实现排列组合算法

命题：从成员数为N的集合S中，选出M个元素，分别求其排列与组合结果集，即 A(N, M)与C(N, M)

js解法：

    <script>
        function queue(arr, size) {
            if (size > arr.length) { return; }
            var allResult = [];

            (function (arr, size, result) {
                if (result.length == size) {
                    allResult.push(result);
                } else {
                    for (var i = 0, len = arr.length; i < len; i++) {
                        var newArr = [].concat(arr),
                            curItem = newArr.splice(i, 1);
                        arguments.callee(newArr, size, [].concat(result, curItem));
                    }
                }
            })(arr, size, []);

            return allResult;
        }


        function choose(arr, size) {
            var allResult = [];

            (function (arr, size, result) {
                var arrLen = arr.length;
                if (size > arrLen) {
                    return;

                }
                if (size == arrLen) {
                    allResult.push([].concat(result, arr))

                } else {
                    for (var i = 0; i < arrLen; i++) {
                        var newResult = [].concat(result);
                        newResult.push(arr[i]);

                        if (size == 1) {
                            allResult.push(newResult);

                        } else {
                            var newArr = [].concat(arr);
                            newArr.splice(0, i + 1);
                            arguments.callee(newArr, size - 1, newResult);

                        }

                    }

                }

            })(arr, size, []);

            return allResult;

        }

        function showResult(result) {
            console.log('The number of result sets: ' + result.length);
            for (var i = 0, len = result.length; i < len; i++) {
                console.log(result[i]);

            }

        }

        var arr = [1,2,3,4,5];
       
        showResult(choose(arr, 4));
        showResult(queue(arr, 4));
    </script>

 原文链接：http://www.cnblogs.com/kaiye/p/3606373.html