Given a very large number X that has n digits, delete k (1 <= k < n <= 5*10^5) digits from it so that the remain part is as large as possible.
First line: Two numbers n & k.
Second line: Number X (without leading zero)
The largest number can be obtained after deleting k digits from it.
- Sample test:
I has met this problem more than five times in my life, but I can't find a solution for this. It would be appreciated if someone help me with this.