Apr 2020
10 / 10
Apr 2020
Apr 2020
thushar_ke25
Apr '20

#include<stdio.h>
#include<math.h>
int main(){
long long int testcases,factors=0,num,j,i;
scanf("%lld",&testcases);

long long int uppbd[testcases],lwrbd[testcases];

for( i=0;i<testcases;i++)
scanf("%lld %lld",&lwrbd[i],&uppbd[i]);

for( i=0;i<testcases;i++){
    
    for(num=lwrbd[i];num<=uppbd[i];num++){
        factors=3;
        
        if(num<=3&&num>1)
          factors=2;
        else{
            if(((num-1)%6==0||(num+1)%6==0)&&(num>4))
            factors=2;
        }
        
        if(factors==2)
        	printf("%lld\n",num);
    
    }

    
    printf("\n");
}
return 0;

}

narbej
Apr '20
1

Maybe because without submitting it’s not possible? [to get WA :wink: ]
Or maybe because your code write wrong answers?

Please tell me, how much and for how big numbers did you test your program?

thushar_ke25
Apr '20

I’ve tested it with
1
1 100000
it’s running fine.
please help me bro I’am stuck
(form past 4 days I’ve been doing this)

narbej
Apr '20
2

Ok, very well, than how you check it?
Please make small test:
1
1 100

You could find correct answers on net, but I give you:

List of prime numbers up to 100: 
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97,

Please compare that list with answer of your program.

Or plese look for that. It’s show your’s wrong method of prepare prime. Bolded and in [ ] number are of course wrong.
2, 3, 5, [6], 7, 11, [12], 13, 17, [18], 19, 23, [24], 25, 29, [30], 31, 35, [36], 37, 41, [42], 43, 47, [48], 49, 53, [54], 55, 59, [60], 61, 65, [66], 67, 71, [72], 73, 77, [78], 79, 83, [84], 85, 89, [90], 91, 95, [96], 97
…
or in other form:

n*6  your prime - n*6 +\- 1
0      2, 3  <- it's out of rule
6      5, 7
12    11, 13
18    17, 19
24    23, 25 <--- first wrong
.......
72   71, 73
etc
simes
Apr '20

How odd, when I ran it with the same input, I got a different list

2, 3, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 37, 41, 43, 47, 49, 53, 55, 59, 61, 65, 67, 71, 73, 77, 79, 83, 85, 89, 91, 95, 97

Still wrong though.

simes
Apr '20
thushar_ke25

The point is though, the problem was very easy to spot from a simple test. This is something you could have, and should have, done for yourself. To claim you’d tested 1 to 100000 and “it’s running fine” was clearly nonsense.