求指导为什么正确率总是0，而且答对的题数好像也不对为啥呀应该怎么改正呢求指导
import java.util.;
public class Game {
public static void main(String[] args) {
Scanner sca=new Scanner(System.in);
System.out.println("请输入题目数：");
int n=sca.nextInt();
int result=0,right=0;
double accuracy;
Random r=new Random();
for(int i=0;i<n;i++) {
int i1=r.nextInt(50);
int i2=r.nextInt(50);
int i3=r.nextInt(2);
if(i3==0) {
result=i1-12;
System.out.println(i1+"-"+i2+"=");}
else {
result=i1+i2;
System.out.println(i1+"+"+i2+"=");}
int a=sca.nextInt();
if(a==result) {
right+=1;
}}
accuracy=right/n;
long startTime=System.currentTimeMillis();
int sum=0;
for(int i=0;i<5000000;i++) {
sum+=i;
}
long endTime=System.currentTimeMillis();
System.out.print("答对了"+right+"题"+","+"正确率:"+accuracy100+"%"+","+"用时："+(endTime-startTime)+"秒");
sca.close();}
}
