单词统计问题

华为OJ
输入一行英文文本，要求输出出现频率最高和最低的单词，中间以,.和空格进行分割，大小不同的单词视为同一个，如果单词数目相同，则输出第一次出现的那个。输出均为小写形式。如”Hello world, i said hello world to the world.”输出world,i
代码如下：

#include <iostream>
#include<vector>
#include<string>
#include<algorithm>
using namespace std;
bool cmp(pair<string,int> data,pair<string,int> data2)
{
    return (data.second > data2.second);
}
int main()
{   
    string patter =", .";
    string source ="Hello world, i said        hello world to the world....";
    transform(source.begin(),source.end(),source.begin(),tolower);
    vector<string> result;
    int size = source.size();
    int i = 0;
    for(;i < size;i++)
    {
        auto found = source.find_first_of(patter,i);
        if(found != string::npos)
        {
            result.push_back(source.substr(i,found-i));
            i = found;
        }
        else
            break;
    }
    if(i != size-1)
    {
        result.push_back(source.substr(i));
    }
    for(auto it = result.begin();it != result.end();)
    {
        if(*it == "" || *it =="." || *it ==",")
            it = result.erase(it);
        else
            ++it;
    }
    vector<pair<string,int>> r;
    for(int i = 0;i < result.size();++i)
    {
        r.push_back(make_pair(result[i],1));
        for(int j = 0;j < r.size()-1;++j)
        {
            if(result[i] == r[j].first)
            {
                r[j].second++;
                r.pop_back();
                break;
            }   
        }
    }
    stable_sort(r.begin(),r.end(),cmp);
    cout<<r[0].first<<",";
    for(int i = 0;i < r.size();++i)
    {
        if(r[i].second == 1)
        {
            cout<<r[i].first<<endl;
            break;
        }
    }
}