排序结构和数组

Question

我的任务是读入一个包含游戏名称和分数的文件（文件看起来像）

5
John Doe 200
Chris Brown 340
Chris Brown 320
John Smith 300
John Doe 600

并按字母顺序（姓氏）打印出该人得分最高的姓名。所以输出看起来像：

Chris Brown 340
John Doe 600
John Smith 300

我想出了如何从最高到最低对分数进行排序和打印，但我不知道如何仅打印每个人的最高分数……任何帮助将不胜感激！

#include <iostream>
#include <fstream>
using namespace std;

struct playerscore
{
    string first, last;
    int score;
};

bool score(playerscore a, playerscore b);
void selectionsort(playerscore *A, int n);

int main()
{
    string file;
    int n;
    cin >> file;
    ifstream fin(file.c_str());
    fin >> n;

    // read in the names and the scores in the form of struct playerscore
   playerscore *A = new playerscore[n];
    for(int i = 0; i < n; i++)
        fin >> A[i].first >> A[i].last >> A[i].score;

    // sort the data
    selectionsort(A, n);

    // print in sorted order
    for(int i = 0; i < n; i++)
        cout << A[i].score << " ";
    cout << endl;

    return 0;
}

bool before(playerscore a, playerscore b)
{
    return a.score > b.score;
}
void selectionsort(playerscore *A, int n)
{
    for(int length = n; length > 1; length--)
    {
        //find imax, index of largest
        int imax = 0, i;
        for(i = 1; i < length; i++)
            if(before(A[imax], A[i]))
                imax = i;
        // swap A[imax] and the last element
        playerscore temp = A[imax];
        A[imax] = A[length-1];
        A[length-1] = temp;
    }
}

Answer 1

1. 按名称升序排序。 如果比较的名称相同，则得分较高的元素应位于数组的较早位置。
2. 打印第一个元素和名称与前一个元素不同的元素。

示例实现：

#include <iostream>
#include <fstream>
using namespace std;

struct playerscore
{
    string first, last;
    int score;
};

bool score(playerscore a, playerscore b);
void selectionsort(playerscore *A, int n);

int main()
{
    string file;
    int n;
#if 0
    cin >> file;
    ifstream fin(file.c_str());
#else
#define fin cin // to test with online compiler
#endif
    fin >> n;

    // read in the names and the scores in the form of struct playerscore
   playerscore *A = new playerscore[n];
    for(int i = 0; i < n; i++)
        fin >> A[i].first >> A[i].last >> A[i].score;

    // sort the data
    selectionsort(A, n);

    // print in sorted order
    for(int i = 0; i < n; i++)
        if (i == 0 || A[i].first != A[i - 1].first || A[i].last != A[i - 1].last)
            cout << A[i].first << " " << A[i].last << " " << A[i].score << "\n";
    cout << endl;

    return 0;
}

bool before(playerscore a, playerscore b)
{
    return a.first == b.first ? (a.last == b.last ? a.score > b.score : a.last < b.last) : a.first < b.first;
}
void selectionsort(playerscore *A, int n)
{
    for(int length = n; length > 1; length--)
    {
        //find imax, index of largest
        int imax = 0, i;
        for(i = 1; i < length; i++)
            if(before(A[imax], A[i]))
                imax = i;
        // swap A[imax] and the last element
        playerscore temp = A[imax];
        A[imax] = A[length-1];
        A[length-1] = temp;
    }
}

Answer 2

您已经完成了困难的部分。

假设((first, last), score)对已经排序，每个玩家的最高分是该玩家的第一条记录，所以访问数组时保持当前玩家的名字为curr_name：

1. 如果下一个名称与curr_name 相同，您可以放心地忽略此项。
2. 如果没有，请打印此记录并更新curr_name。

代码就像自爆了：

#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#include <string>
#include <utility>
using namespace std;
bool mycmp (pair<pair<string, string>, int> a, pair<pair<string, string>, int> b) {
    return a.first < b.first || (a.first == b.first && a.second > b.second);
}
int main(int argc, char *argv[])
{
    ifstream fin("data.txt");
    int n;
    fin>>n;
    vector<pair<pair<string, string>, int>> A(n);
    for(int i = 0; i < n; ++i){
        fin>>A[i].first.first>>A[i].first.second>>A[i].second;
    }
    sort(A.begin(), A.end(), mycmp);
    pair<string, string> cur_name;
    for(int i = 0; i < n; ++i){
        if(cur_name != A[i].first){
            cout<<A[i].first.first<<" "<<A[i].first.second<<" "<<A[i].second<<endl;
            cur_name = A[i].first;
        }
    }
    return 0;
}

Answer 3

如前所述，由于这是一项任务，我决定重写代码，它现在应该是这样的。

1. 根据分数对数组进行排序

2. 按字母顺序对数组进行排序

3. 打印唯一条目

   #include <iostream>
   #include <fstream>
   using namespace std;
   
   struct playerscore
   {
       string first, last;
       int score;
   };
   
   bool score(playerscore a, playerscore b);
   void selectionsort(playerscore *A, int n);
   
   int main()
   {
       string file;
       int n;
       cin >> file;
       ifstream fin(file.c_str());
       fin >> n;
   
       // read in the names and the scores in the form of struct playerscore
       playerscore *A = new playerscore[n];
       for (int i = 0; i < n; i++)
           fin >> A[i].first >> A[i].last >> A[i].score;
   
       // sort the data
       selectionsort(A, n);
       // sort alphabetically and print unique entries
       for (int i=0; i<n-1; i++)
       {
           for (int j=i+1; j<n; j++)
           {
               if (A[j].last <= A[i].last && A[j].first < A[i].first)
               {
                   playerscore tmp = A[i];
                   A[i] = A[j], A[j] = tmp;
               }
        }
   
        playerscore max;
        int j = 0;
        for (int i=0; j+i<n; i++)
        {
            max.score = -1;
   
            while (j+i<n && A[j+i].last == A[i].last && A[j+i].first == A[i].first)
            {
                if (A[j+i].score >= A[i].score)
                    max = A[j+i];
                j++;
            }
            j--;
   
            if (max.score >= 0)
                cout << max.last << " " << max.first << " " << max.score << endl;
        }
        cout << endl;
   
        return 0;
    }
   
    bool before(playerscore a, playerscore b)
    {
         return a.score > b.score;
    }
   
    void selectionsort(playerscore *A, int n)
    {
        for(int length = n; length > 1; length--)
        {
            //find imax, index of largest
            int imax = 0, i;
            for(i = 1; i < length; i++)
                if(before(A[imax], A[i]))
                    imax = i;
            // swap A[imax] and the last element
            playerscore temp = A[imax];
            A[imax] = A[length-1];
            A[length-1] = temp;
        }
    }