#include <stdio.h>

struct Student 
{
	char cSchool[15];
    char cGrade[15];
	char cName[15];		
};

int test();						
int checknum(int a,int b);
int checkresult(int x);      /*函数说明*/    

int a=-1,b,c,x;
int k=0,grade;           /*定义所需要的参数*/

int main()
{
   	struct Student student1;
	printf("****预祝测试顺利****\n\n");
	printf("学校:");
	scanf("%s",&student1.cSchool);
	printf("年级:");
	scanf("%s",&student1.cGrade);
	printf("姓名:");
	scanf("%s",&student1.cName);
    printf("\n");
	 
    printf("请回答下面十道题目\n");
	
	do{
		int i=test();
		if(i==-1)
		{
			if(grade>=90)
				printf("-------SMART");
			else if(grade>=80&&grade<90)
				printf("-------GOOD");
			else if(grade>=70&&grade<80)
				printf("-------OK");
			else if(grade>=60&&grade<70)
			    printf("-------PASS");
			else
				printf("-------TRY AGAIN");	
			break;
		}
		else if(checkresult(i)==0){
			a=-1;
		}
	}while(k);
	return 0;
}

int test()
{
	srand((unsigned int)time(NULL));
	while(checknum(a,b)==0)			/*若返回0，则重新取值；若返回1，则完成a,b取值*/ 
	{
		a=rand()%51;            	/*a取值范围0~50*/
		b=rand()%51;              	/*b取值范围0~50*/
		c=rand()%2;	            	/*c取值范围0~1*/
	}
	k++;                            /*k表示第几题*/
	if(k==11)
	{
		printf("\n所有题目已答完，你的成绩：%d分",grade); 
		return -1;
		}
	else if(c==0)
	{
		printf("第%d题:%d+%d=",k,a,b);
		return a+b; 
		}
	else if(c==1)
	{
		printf("第%d题:%d-%d=",k,a,b);
		return a-b;
		}
	return -1;	
}

int checknum(int a,int b)			/*检查相加或相减的两个数是否满足要求*/
{
	if(a>50||b>50||a<0||b<0||(a+b)>50||(a-b)<0)
		return 0;
	else
		return 1;
 } 
 
 int checkresult(int result)
 {
    int i;
    for(i=1;i<4;i++)
	{
        scanf("%d", &x);
        if (x!=result)
		{
            if (i==3)
			{
                if (c==0){
                    printf("三次回答错误，正确答案是%d\n",a+b);
                }
                else {
                    printf("三次回答错误，正确答案是%d\n",a-b);
                }
                return 0;
            }
            printf("回答错误,请再次输入：");
        }
		else{
			switch(i){
						case 1:grade+=10;
								break;
						case 2:grade+=7;
								break;
						case 3:grade+=5;
								break;
						default:grade+=0;
								break;
				     }
		    		 return 0;    		     
			}
	}
	return 0;
 }