# Smallest number with sum of digits as N and divisible by 10^N

Find the smallest number such that the sum of its digits is N and it is divisible by 10N.

Example 1:

```
Input: N = 5
Outptut: 500000
Explanation: Sum of digits of 500000
is 5 and divisible by 105.
```

Example 2:

```
Input: N = 20
Output: 29900000000000000000000
Explanation: Sum of digits of
29900000000000000000000 is 20 and
divisible by 1020.
```

**method : greedy approach**

**c++ implementation:**

string digitsNum(int n) { string r=""; int t=n/9; int z=n-t*9; if(z!=0) r=r+to_string(z); while(t--) { r=r+"9"; } while(n--) { r=r+"0"; } return r; }

**Time Complexity:**O(n)

**space Complexity:**O(n)