# Leetcode Lexicographical Number problem solution

In this Leetcode Lexicographical Number problem solution you have given an integer n, return all the numbers in the range [1, n] sorted in lexicographical order. You must write an algorithm that runs in O(n) time and uses O(1) extra space.

## Problem solution in Python.

```class Solution:
def lexicalOrder(self, n: int) -> List[int]:
l = list()
for i in range(1,n+1):
l.append(str(i))
l.sort()
i = len(l)-1
while i>0:
l[i] = int(l[i])
i-=1
l[i] = int(l[i])
return l
```

## Problem solution in Java.

```public List<Integer> lexicalOrder(int n) {
int num = 1;
List<Integer> results = new ArrayList<>();
while (true) {
if (num <= n) {
num *= 10;
continue;
}

num /= 10;
while (num % 10 == 9 && num != 0)
num /= 10;
if (num == 0)
return results;
num += 1;
}
}
```

## Problem solution in C++.

```class Solution {
int next(int last, int n)
{
if (last * 10 <= n)
return last * 10;
if (last == n)
last /= 10;
++last;
while(last % 10 == 0)
last /= 10;
return last;
}
public:
vector<int> lexicalOrder(int n) {
if (n < 1) return vector<int>();
vector<int> result(n);
result[0] = 1;
for (int i = 1; i < n; ++ i)
result[i] = next(result[i - 1], n);
return result;
}
};
```