Using Stack Concept - 7 liner || Very Simple & Easy to understand solution
Approach \nKeep pushing values to stack( here ans string is used as stack ), and each value remove elements from stack top, if top element is larger then presen
# Approach \nKeep pushing values to stack( here ans string is used as stack ), and each value remove elements from stack top, if top element is larger then present element. Do this for k times.\nAt the end, total on the stack  & remaining num unprocessed data will be the answer.\nHere string variable is used as stack.\n\n\n```\n  string removeKdigits(string num, int k) {\n      string ans = "";\n      for(auto c: num){\n          while(ans.size() && c < ans.back() && k) { ans.pop_back(); k--; }\n          if(ans.size() + (c - \'0\')) ans.push_back(c);\n      }\n      while(k-- && ans.size()) ans.pop_back(); \n      return ans.size()?ans: "0";\n  }\n\n```
['C++']