切分字串，統計詞頻。

//6-21
#include <iostream>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

const int MAXN = 100;

void split(const std::string& s, std::vector<std::string>& v, const std::string& c)
{
  std::string
 
::size_type pos1, pos2;
  pos2 = s.find(c);
  pos1 = 0;
  while(std::string::npos != pos2)
  {
    v.push_back(s.substr(pos1, pos2-pos1));

    pos1 = pos2 + c.size();
    pos2 = s.find(c, pos1);
  }
  if(pos1 != s.length())
    v.push_back(s.substr(pos1));
}

int main(){
    string str;
    vector<string
 
> vec;
    vector<string> key;
    getline(cin,str);
    split(str,key," ");
    while(getline(cin,str)){
        split(str,vec," ");
    }
    vector<string>::iterator it;

    sort(vec.begin(),vec.end());
    /*
    for(it = vec.begin();it != vec.end();it ++){
        cout<< *it <<endl;
    }*/
 

    for(int i=0;i<key.size();i++){
        int counts = count(vec.begin(),vec.end(),key[i]);
        cout<< key[i] << ": " << counts <<endl;
    }

    return 0;
}
/*
this is a book

It is a cat this book This is book
that is a tree


 */