# 12.25.2021 - Algorithms / Generate repeated combinatorial

The algorithm is simple:

- Find the right most element less than n
- Increase it
- Set the other right the same

It can be implemented as following:

```
const next = (r) => {
let n = r.length;
for (let i = n - 1; i >= 0; i--) {
if (r[i] < n) {
r[i]++;
for (let j = i; j < n; j++) {
r[j] = r[i];
}
return r;
}
}
return null;
};
```

And here’s how we would use it:

```
let gen = next([0, 0, 0, 0]);
while (gen != null) {
console.log(gen);
gen = next(gen);
}
```