按重复次数递减的顺序输出汽车名称，不重复，出现次数

#1 楼

map<string, int> *lines = new map<string, int>();
multimap<int, string> *lines_by_count = new multimap<int, string>();

map<string, int>        lines;
multimap<int, string>   lines_by_count;

while (in.good())
{
    getline(in, tmp);

while (getline(in, tmp))
{
    // Line read successfully
    // Now I can processes it
}

    if (lines.count(tmp) == 0)
    {
        lines[tmp] = 0;
    }
    lines[tmp]++;

// trim initial space (also skips empty strings)
for (i = 0; i < tmp.length() && !isalnum(tmp[i]); i++);

    for (i = 0; i < tmp.length(); i++)
    {
        if (!isalnum(tmp[i]))
        {
            tmp[i] = ' ';
        }

#2 楼

map<string, int> *lines = new map<string, int>();
multimap<int, string> *lines_by_count = new multimap<int, string>();
// more things
delete lines;
delete lines_by_count;

map<string, int> lines;
multimap<int, string> lines_by_count;
// things

#3 楼

#include <iostream>
#include <list>
#include <map>

using namespace std;

bool my_pair_compare(pair<string,int> &a, pair<string,int> &b) { 
  return a.second > b.second; 
}

void my_pair_output(pair<string,int> &p) { 
  cout << p.first << " " << p.second << endl; 
}

int main() {
  map<string,int> cars;

  while (1) {
    string name;
    cin >> name;
    if (cin.eof()) break;
    cars[name]++;
  }

  list<pair<string,int> > names;

  map<string,int>::iterator citer = cars.begin();
  while (citer != cars.end()) 
    names.push_back(*citer++);

  names.sort(my_pair_compare);
  for_each(names.begin(), names.end(), my_pair_output);

  return 0;
}

#4 楼

#5 楼

#6 楼

#7 楼

sort cars.txt | uniq -c | sort -rn

#8 楼

#9 楼

#10 楼

// reads lines from instream
void collect_lines(istream &in, map<string, int> &lines);

// given lines->num_occurs map, reverses mapping
void reorg_by_count(map<string, int> &lines, 
                    multimap<int, string> &bycount);

#11 楼

#include <iostream>
#include <map>
#include <vector>

using std::cin;
using std::cout;
using std::map;
using std::pair;
using std::string;
using std::vector;

bool my_pair_less(const pair<string, int> &a, const pair<string, int> &b) {
  return b.second < a.second;
}

void my_pair_output(const pair<string, int> &p) {
  cout << p.first " " << p.second << "\n";
}

int main() {
  map<string, int> cars;

  string name;
  while (getline(cin, name)) {
    cars[name]++;
  }

  vector<pair<string, int> > names;
  copy(cars.begin(), cars.end(), back_inserter(names));
  sort(names.begin(), names.end(), my_pair_less);

  for_each(names.begin(), names.end(), my_pair_output);

  return 0;
}

#12 楼

#13 楼

#include <string>
#include <iostream>
#include <fstream>
#include <map>
#include <set>
#include <vector>

using namespace std;

int main( int numberOfArguments, char** arguments )
{
    typedef map< string, unsigned int > CarEntryMap;

    typedef pair< unsigned int, CarEntryMap::iterator > CarFrequency;

    typedef vector< CarFrequency > CarFrequencyVector;

    fstream file( "C:\Cars.txt" );

    if( !file.is_open() )
    {
        return 0;
    }

    CarEntryMap carEntries;

    CarFrequencyVector carFrequencies;

    string carName = "";

    while( getline( file, carName ) )
    {
        CarEntryMap::iterator it = carEntries.find( carName );

        if( it == carEntries.end() )
        {
            CarEntryMap::iterator entry = carEntries.insert( it, pair< string, unsigned int >( carName, carFrequencies.size() ) );

            carFrequencies.push_back( CarFrequency( 1, entry ) );
        }
        else
        {
            unsigned int index = it->second;

            pair< unsigned int, CarEntryMap::iterator >& currentEntry = carFrequencies[ index ];

            currentEntry.first++;

            if( index != 0 )
            {
                unsigned int updatedIndex = index;

                for( int i = index - 1; i >= 0; i-- )
                {
                    if( currentEntry.first <= carFrequencies[i].first )
                    {
                        break;
                    }

                    updatedIndex = i;
                }

                if( index != updatedIndex )
                {
                    carFrequencies[ updatedIndex ].second->second = index;

                    currentEntry.second->second = updatedIndex;

                    swap( carFrequencies[ updatedIndex ], currentEntry );
                }
            }
        }
    }

    for( CarFrequencyVector::iterator it = carFrequencies.begin(); it != carFrequencies.end(); ++it )
    {
        cout << it->second->first << " " << it->first << endl;
    }

    return 0;
}

#14 楼

struct sort_pred {
    bool operator()(const std::pair<string,int> &left, const std::pair<string,int> &right) {
        return left.second > right.second;
    }
};

int main()
{
   multiset< pair<string,int> ,sort_pred > myset;
   map<string,int> mymap;
   readfile(mymap);
        for(map<string,int>::iterator it=mymap.begin();it!=mymap.end();it++)
        {
                myset.insert(make_pair<string,int>(it->first,it->second));
        }
        cout<<"Elements in the set:"<<endl;
        for(multiset<pair<string,int>,sort_pred >::iterator it=myset.begin();it!=myset.end();it++)
                cout<<it->first<<" "<<it->second<<endl;
                return 0;
}

void readfile(map<string,int> &t)
{
       string filename="temp.txt";
       ifstream file;
       file.open(filename.c_str());

       if(!file.is_open())
       {
              cerr<<"Error opening file : "<<filename.c_str()<<endl;
              exit(0);
       }

      string line;
      while(getline(file,line))
      {
          if(t.find(line)!=t.end())
                  t[line]++;
                  else
                  t.insert(std::make_pair(line,1));
      }
}

#15 楼

#16 楼