Come on leetcode...

```
int uniquePaths(int m, int n) {
// (m+n-2) Combination (n-1)
int right = min(m, n) - 1, left = m + n - 2;
int iter = right;
double ret = 1;
for (int i = 1; i <= iter; i++)
{
ret *= left--;
ret /= right--;
}
return round(ret);
}
```