Class Solution

LeetCode_problems/Length of Last Word/solution.cpp:7–34

class Solution {
public:
    std::string & ltrim(std::string & str)
    {
      auto it2 =  std::find_if( str.begin() , str.end() , [](char ch){ return !std::isspace<char>(ch , std::locale::classic() ) ; } );
      str.erase( str.begin() , it2);
      return str;                                             // returns the string with no extra blank spaces at the front.
    }

    std::string & rtrim(std::string & str)
    {
      auto it1 =  std::find_if( str.rbegin() , str.rend() , [](char ch){ return !std::isspace<char>(ch , std::locale::classic() ) ; } );
      str.erase( it1.base() , str.end() );                                            
      return str;                                             // returns the string with no extra blank spaces at the back.
    }
    
    int lengthOfLastWord(string s) {
        s = ltrim(rtrim(s));            // removes extra spaces fromfront and back of string
        string t = "";
        for(char c: s){                 // iterate through the string to get all words and finally having last word in string t.
            if(c == ' ')
                t = "";
            else
                t += c;                 
        }
        return t.size();                // returns the size of t which contains the last word.
    }
};