输入n个学生，并且输入成绩，判断是否偏科

       H学校的领导主任决定分析一下今年所有N名学生的考试成绩，从中找出偏科的学生，考试成绩包含语文，数学，英语三门课程的分数，已知偏科的定义是：某一门课程的分数大于等于90，并且另外两门的分数小于等于70。

请你求出一共有多少名偏科的学生。

输入第一行包含一个整数N。

以下N行每行包含三个整数，Ai,Bi,Ci，依次是语文，数学，英语的分数。

1<=N<=10000

0<=Ai,Bi,Ci<=100

输出

一个整数代表答案

首先应该先写出学生类：

public class StudentDemo {
    private int lanGrade;//语文成绩
    private int mathGrade;//数学成绩
    private int engGrade;//英语成绩
    public StudentDemo(int lanGrade,int mathGrade,int engGrade){
        this.lanGrade = lanGrade;
        this.engGrade = engGrade;
        this.mathGrade = mathGrade;
    }

    public int getLanGrade() {
        return lanGrade;
    }

    public void setLanGrade(int lanGrade) {
        this.lanGrade = lanGrade;
    }

    public int getMathGrade() {
        return mathGrade;
    }

    public void setMathGrade(int mathGrade) {
        this.mathGrade = mathGrade;
    }

    public int getEngGrade() {
        return engGrade;
    }

    public void setEngGrade(int engGrade) {
        this.engGrade = engGrade;
    }

    @Override
    public String toString() {
        return "StudentDemo{" +
                "lanGrade=" + lanGrade +
                ", mathGrade=" + mathGrade +
                ", engGrade=" + engGrade +
                '}';
    }
}

创建成绩类：（判断）

import java.util.Scanner;

public class GradeTest {
    private StudentDemo[] studentDemos;
    private int studentNum;
    private Scanner sc;
    public GradeTest(){
        this.sc = new Scanner(System.in);
        this.studentNum = 0;
        this.studentDemos = new StudentDemo[1000];
        this.studentDemos[this.studentNum++] = new StudentDemo(0,0,0);
    }


    public static void main(String[] args) {
        GradeTest gd = new GradeTest();
        gd.setGrade();
        int num = gd.search();
        System.out.println("偏科人数："+num);

    }

    private void setGrade() {
            System.out.println("请输入学生个数：");
            int num = sc.nextInt();
            System.out.println("请输入学生成绩（成绩大于等于0小于等于100）：");
               int i = 1;
               while (i <= num) {
                   int lanGrade = sc.nextInt();
                   int mathGrade = sc.nextInt();
                   int engGrade = sc.nextInt();
                   if (i == studentNum) {
                       studentDemos[this.studentNum++] = new StudentDemo(lanGrade, mathGrade, engGrade);
                   }
                   i++;
               }

    }

    public int search() {
        int count = 0;
            for (int i = 0; i < this.studentNum; i++) {
                if ((studentDemos[i].getEngGrade() >= 90 && studentDemos[i].getLanGrade() <= 70 && studentDemos[i].getMathGrade() <= 70) ||
                        (studentDemos[i].getLanGrade() >= 90 && studentDemos[i].getEngGrade() <= 70 && studentDemos[i].getMathGrade() <= 70) ||
                        (studentDemos[i].getMathGrade() >= 90 && studentDemos[i].getLanGrade() <= 70 && studentDemos[i].getEngGrade() <= 70)) {
                    count++;
                }
            }
            return count;
        }
}

运行结果如图：