Reverse Words in a String

Given an input string, reverse the string word by word.

For example,
Given s = "the sky is blue",
return "blue is sky the".

click to show clarification.

Clarification:

 

• What constitutes a word?
  A sequence of non-space characters constitutes a word.
• Could the input string contain leading or trailing spaces?
  Yes. However, your reversed string should not contain leading or trailing spaces.
• How about multiple spaces between two words?
  Reduce them to a single space in the reversed string.

些麻烦了，懒得改。对于空格，只要while就能解决。

注意，string 和 char *是不一样的。

 

class Solution {
public:
    void reverseWords(string &s) {
        stack<string> sk;
        if(s.size()==0)return ;
        int i = 0;
        int b = 0,e = 0;
        if(s.size()==1)
        {
            if(s[0] == ' ')
            {
                s = "";
                return;
            }
            else return;
        }
        for(i = 0 ; i < s.size()-1;i++)
        {
            if(s[i] == ' '&&s[i+1] != ' ')
            {
                b = i+1;
            }
            else if(s[i] != ' ' && s[i+1] == ' ')
            {
                e = i+1;
                string tp = s.substr(b,e-b);
                sk.push(tp);
            }
        }
        if(s[s.size()-1] != ' ')
        {
            string tp = s.substr(b,s.size());
          //  if(b != e)
            {
                sk.push(tp);
            }
        }
        
        if(sk.empty())
        {
            s="";
            return;
        }
        s = sk.top();
        sk.pop();
        
        while(!sk.empty())
        {
            string tp = sk.top();
            s = s + ' '+tp;
            sk.pop();
        }
        //s = s+'\0';
    }
};