Remove K Digits.cpp

/*
Remove K Digits
Solution
Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible.

Note:
The length of num is less than 10002 and will be ≥ k.
The given num does not contain any leading zero.
Example 1:

Input: num = "1432219", k = 3
Output: "1219"
Explanation: Remove the three digits 4, 3, and 2 to form the new number 1219 which is the smallest.
Example 2:

Input: num = "10200", k = 1
Output: "200"
Explanation: Remove the leading 1 and the number is 200. Note that the output must not contain leading zeroes.
Example 3:

Input: num = "10", k = 2
Output: "0"
Explanation: Remove all the digits from the number and it is left with nothing which is 0.

*/

class Solution {
public:
    string removeKdigits(string num, int k) {
        if(k == num.length())
            return "0";
        
        int cnt=0;
        while(k-- != 0)
        {
            for(int i=0;i<num.length()-1;i++)
            {
                if((num[i]-'0') > (num[i+1]-'0'))
                {
                    num.erase(i,1);
                    break;
                }else if(i==num.length()-2)
                {
                    num.erase(i+1,1);
                }
            }
        }
        for(int i=0;i<num.length();i++)
        {
            if(num[i] != '0')
            {
                break;
            }else
            {
                num.erase(i,1);
                i--;
            }
        }
        if(num.length() == 0 )
            return "0";
        return num;
    }
};