我不断收到错误消息“超过了时间限制".在C程序中.如何提高代码效率?

Peter想为其密码系统生成一些质数.救救他！您的任务是生成两个给定数字之间的所有质数！输入以一行中的测试用例数 t 开始( t< = 10 ).在接下来的每个 t 行中，有两个数字 m 和 n ( 1< = m< = n<= 1000000000，n-m )，以空格分隔.

Peter wants to generate some prime numbers for his cryptosystem. Help him! Your task is to generate all prime numbers between two given numbers! The input begins with the number t of test cases in a single line (t <= 10). In each of the next t lines there are two numbers m and n (1 <= m <= n <= 1000000000, n - m<=100000) separated by a space.

我不知道如何用高级概念解决问题，所以我只使用循环来解决它.

I don't know how to solve the problem with advanced concepts so I solved it by using just loops.

此问题的时间限制为6.00s

The time limit to this problem is 6.00s

#include <stdio.h>
int main(void)
{
    int a[1],b[1],j,i,test,k,flag;
    scanf("%d",&test);
    for(i=1;i<=test;i++)
    {
        for(k=0;k<1;k++)
        {
            scanf("%d %d",&a[k],&b[k]);
        }
        for(j=a[0];j<=b[0];++j)
        {
            flag=0;
            for(k=2;k<j;++k)
            {
                if(j%k==0)
                {
                    flag=1;
                    break;
                }
            }
            if(flag==0)
            {
                printf("\n%d",j);
            }
        }
    }
    return 0;
}