//學生成績管理。

#include <iostream.h>
#include "SinglyLinkedList.h"                         //單鏈表類
#include "Student.h"                                  //例2.2的學生結構

double average(SinglyLinkedList<Student> &stulist)    //求平均值
{
    int n=stulist.length();                           //單鏈表長度
    if (n>0)
    {
        double sum=0;
        for (int i=0; i<n; i++)
             sum += stulist.get(i).score;             //此處get(i)返回Student結構類型
        return sum/n;
    }
    return 0.0;                                       //給出0個元素的結果，避免除數為0錯誤
}

void printGrade(SinglyLinkedList<Student> &stulist)       //按優、良、中、及格、不及格五個等級統計人數
{
    int n=stulist.length();
    if (n>0)
    {
        int grade[5] = {0};
        for (int i=0; i<n; i++)
        {
             double x= stulist.get(i).score;
             if (x>=90 && x<=100)
                 grade[0]++;
             else if (x>=80 && x<90)
                 grade[1]++;
             else if (x>=70 && x<80)
                 grade[2]++;
             else if (x>=60 && x<70)
                 grade[3]++;
             else if (x>=0)
                 grade[4]++;
        }
        cout<<"優秀"<<grade[0]<<"，良好"<<grade[1]<<"，中等"<<grade[2]<<"，及格"<<grade[3]<<"，不及格"<<grade[4]<<endl;
    }
}

int main()
{
    Student group[]={{"20208301","王紅",80},{"20208302","張明",75},{"20208303","李強",90},
                     {"20208304","鄭小春",80},{"20208305","陳新諾",60},{"20208306","吳寧",65}}; 
    SinglyLinkedList<Student> stulist(group,6);            //由指定數組構造單鏈表
    Student stu={"20208307","崔小兵",70};
    stulist.insert(stu);                                   //參數為Student結構類型
    cout<<"學生成績表（"<<stulist.length()<<"人）：";
    stulist.print();
    printGrade(stulist);
    cout<<"平均成績："<<average(stulist)<<endl;
    if (stulist.remove(0, stu))                            //被刪除元素在stu結構變量中
        cout<<"刪除了"<<stu.name<<endl;
    return 0;
}

/*
程序運行結果如下：
學生成績表（7人）： ((20208301,王紅,80), (20208302,張明,75), (20208303,李強,90), (20208304,鄭小春,80), (20208305,陳新諾,60), (20208306,吳寧,65), (20208307,崔小兵,65))
優秀1，良好2，中等2，及格2，不及格0
平均成績：74.2857
刪除了王紅

*/