4.Reverse Words in a String-Leetcode

class Solution {public:    void reverseWords(string &s) { vector<string> data;        string word;        stringstream ss(s);        while(ss>>word) data.push_back(word);        vector<string> rdata(data.rbegin(), data.rend());        s = accumulate(rdata.begin(), rdata.end(), string(""),            [](string s1, string s2){                if(s1.empty()) return s2;                else return s1+" "+s2;             });    }};

class Solution {public:    void reverseWords(string &s) {        for(string::size_type ix=0;ix!=s.size();++ix)        {            if(s[ix]==' ')                if(s[ix+1]==' '){                    s.erase(ix,1);                    ix--;                }               }        if(s[0]==' ')s.erase(0,1);        if(s[s.size()-1]==' ')s.erase(s.size()-1,1);        int k=0;        string st(s.size(),'a');        for(string::size_type ix=s.size()-1;ix!=-1;--ix)//全倒置         {            st[k++]=s[ix];        }        int beg=0,end=0,n=st.size();        int index=0;        while(end<=n)        {            while(st[end]!=' '&&end<n)end++;            for(int i=end-1;i>=beg;--i)s[index++]=st[i];            if(st[end]==' ')s[index++]=' ';            end=end+1;            beg=end;        }           }};