js实现重复的排列组合

function rp(arr, count) {
var result = [];
var cal = function(r, a, c) {
if (c == 0) {
result.push(r);
return;
}
for (var i = 0; i < a.length; i++) {
cal(r.concat(a[i]), a.slice(0, i + 1).concat(a.slice(i + 1)), c - 1);
}
};
cal([], arr, count);
return result;
}

function run() {
var r = rp([1, 2, 3, 4, 5], 3);
console.debug(r);
console.debug(r.length);
}

结果:

[[1, 1, 1], [1, 1, 2], [1, 1, 3], [1, 1, 4], [1, 1, 5], [1, 2, 1], [1, 2, 2], [1, 2, 3], [1, 2, 4], [1, 2, 5], [1, 3, 1], [1, 3, 2], [1, 3, 3], [1, 3, 4], [1, 3, 5], [1, 4, 1], [1, 4, 2], [1, 4, 3], [1, 4, 4], [1, 4, 5], [1, 5, 1], [1, 5, 2], [1, 5, 3],
[1, 5, 4], [1, 5, 5], [2, 1, 1], [2, 1, 2], [2, 1, 3], [2, 1, 4], [2, 1, 5], [2, 2, 1], [2, 2, 2], [2, 2, 3], [2, 2, 4], [2, 2, 5], [2, 3, 1], [2, 3, 2], [2, 3, 3], [2, 3, 4], [2, 3, 5], [2, 4, 1], [2, 4, 2], [2, 4, 3], [2, 4, 4], [2, 4, 5], [2, 5, 1], [2,
5, 2], [2, 5, 3], [2, 5, 4], [2, 5, 5], [3, 1, 1], [3, 1, 2], [3, 1, 3], [3, 1, 4], [3, 1, 5], [3, 2, 1], [3, 2, 2], [3, 2, 3], [3, 2, 4], [3, 2, 5], [3, 3, 1], [3, 3, 2], [3, 3, 3], [3, 3, 4], [3, 3, 5], [3, 4, 1], [3, 4, 2], [3, 4, 3], [3, 4, 4], [3, 4,
5], [3, 5, 1], [3, 5, 2], [3, 5, 3], [3, 5, 4], [3, 5, 5], [4, 1, 1], [4, 1, 2], [4, 1, 3], [4, 1, 4], [4, 1, 5], [4, 2, 1], [4, 2, 2], [4, 2, 3], [4, 2, 4], [4, 2, 5], [4, 3, 1], [4, 3, 2], [4, 3, 3], [4, 3, 4], [4, 3, 5], [4, 4, 1], [4, 4, 2], [4, 4, 3],
[4, 4, 4], [4, 4, 5], [4, 5, 1], [4, 5, 2], [4, 5, 3], [4, 5, 4], [4, 5, 5], [5, 1, 1], [5, 1, 2], [5, 1, 3], [5, 1, 4], [5, 1, 5], [5, 2, 1], [5, 2, 2], [5, 2, 3], [5, 2, 4], [5, 2, 5], [5, 3, 1], [5, 3, 2], [5, 3, 3], [5, 3, 4], [5, 3, 5], [5, 4, 1], [5,
4, 2], [5, 4, 3], [5, 4, 4], [5, 4, 5], [5, 5, 1], [5, 5, 2], [5, 5, 3], [5, 5, 4], [5, 5, 5]]