如何找到重复次数最多的单词？

Question

如何让程序打印出重复次数最多的单词？现在它打印如下：

输入： 苹果香蕉苹果苹果

输出：

苹果出现了 3 次

香蕉出现了 1 次

int main() {
        string words;
        vector<string> stringHolder;

        while (cin >> words)
        {
            stringHolder.push_back(words);
        }
        sort(stringHolder.begin(), stringHolder.end());

        int vSize = stringHolder.size();
        if (vSize == 0) {
            cout << " no words ";
        }
        int wordCount = 1;
        words = stringHolder[0];
        for (int i = 1; i<vSize; i++) {
            if (words != stringHolder[i]) {
                cout << words << " appeared " << wordCount << " times" << endl;
                wordCount = 0;
                words = stringHolder[i];
            }
            wordCount++;
        }
        cout << words << " appeared " << wordCount << " times" << endl;
        system("pause");
    }

Answer 1

我会为此使用std::map 和std::set：

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

// typedef for a "word => count" map
using wordcountmap = std::map<std::string, int>;
// typedefs for making a sorted set
using wordcountpair = std::pair<std::string, int>;
using CompareFunc = bool(*)(const wordcountpair&, const wordcountpair&);
using wordcountset = std::set<wordcountpair, CompareFunc>;

wordcountmap make_wordcountmap(const std::vector<std::string>& words)
{
    wordcountmap wcm;
    // map::operator[] is used to access or
    // insert specified element
    for(const std::string& word : words) {
        // std::string has a std::hash specialization
        // https://en.cppreference.com/w/cpp/utility/hash
        // calculating the hash for you
        //
        // If "word" does not exist in the map, it will be inserted
        // with a default constructed value, which is 0 for an int.
        ++wcm[word];
    }
    return wcm;
}

wordcountset make_wordcountset(const wordcountmap& wcm) {
    // populate the set using the maps iterators and provide a comparator
    // lambda function that will sort the set in descending order
    wordcountset wcs(
        wcm.begin(),
        wcm.end(),
        [](const wordcountpair& a, const wordcountpair& b) {
            return b.second==a.second ? b.first<a.first : b.second<a.second;
        }
    );
    return wcs;
}

int main(int argc, char* argv[]) {
    // put all command line arguments in a string vector
    std::vector<std::string> args(argv+1, argv+argc);

    // Your "word => count" map
    wordcountmap MyWCM = make_wordcountmap(args);

    // create a set of <word, count> pairs, sorted in count order.
    wordcountset set_of_sorted_words = make_wordcountset(MyWCM);

    // output the number of times the words appeared
    for(const wordcountpair& element : set_of_sorted_words) {
        // element.first  is the "word" in the wordcountpair
        // element.second is the "value" in the wordcountpair

        std::cout << element.second << " " << element.first << "\n";
    }

    if(set_of_sorted_words.size())
        std::cout << "The winner is " << (*set_of_sorted_words.begin()).first << "\n";

    return 0;
}

输出：

3 apple
1 banana
The winner is apple