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.
Example 1:
Input: n = 13 Output: [1,10,11,12,13,2,3,4,5,6,7,8,9]
Example 2:
Input: n = 2 Output: [1,2]
Constraints:
1 <= n <= 5 * 104class Solution {
List<Integer> ans = new ArrayList<>();
public List<Integer> lexicalOrder(int n) {
for (int i = 1; i < 10; i++)
solve(i, n);
return ans;
}
private void solve(int base, int n) {
if (base > n)
return;
ans.add(base);
for (int i = 0; i < 10; i++)
solve(base * 10 + i, n);
}
}class Solution {
List<Integer> ans = new ArrayList<>();
public List<Integer> lexicalOrder(int n) {
for (int i = 1; i < 10; i++)
solve(String.valueOf(i), n);
return ans;
}
private void solve(String base, int n) {
int val = Integer.parseInt(base);
if (val > n)
return;
ans.add(val);
for (int i = 0; i < 10; i++)
solve(base + i, n);
}
}class Solution {
List<Integer> ans = new ArrayList<>();
public List<Integer> lexicalOrder(int n) {
for (int i = 1; i < 10; i++)
solve(String.valueOf(i), n);
return ans;
}
private void solve(String base, int n) {
int val = Integer.parseInt(base);
if (val > n)
return;
ans.add(val);
for (int i = 0; i < 10; i++)
solve(base + i, n);
}
}