Can someone tell me where i am getting wrong

#1

import java.util.*;
public class PrimeVisits {
public static void main(String args[]) {
Scanner scan=new Scanner(System.in);
// testcases
int t = scan.nextInt();
ArrayList list = new ArrayList<>();
while(t>0){
// input a and b
//boolean flag = true;
int count=0;
int a = scan.nextInt();
int b = scan.nextInt();
for(int i=a;i<=b;i++){
//for ith element
boolean flag = true;
for(int j=2;j<=i-1;j++){
if(i%j==0){
flag=false;
}
}
if(flag==false){
count++;
}
}
list.add(count);
t–;
}
for(int i=0;i<list.size();i++){
System.out.println(list.get(i));
}

}

}

#2

Hi Vaibhav

You basically have to count the prime numbers between a and b in this question. Your code is doing otherwise.
For a = 1 and b = 10, there are 4 prime numbers in between them, i.e., 2, 3, 5, and 7. Hence, the output is 4.

#3

Also, please share your code by pasting it in ide.codingblocks.com first, saving it and then sending the link here. It’ll help us to debug the code better.

#4
#5

Third testcase time limit error import java.util.*; public class Main { public static void main(String args[]) { Scanner scan=new Scanner(System.in); // testcases int t = scan.nextInt(); ArrayList list = new ArrayList<>(); while(t>0){ // input a and b //boolean flag = true; int count=0; int a = scan.nextInt(); int b = scan.nextInt(); int i=a; if(a<=1){ i=2; } for(;i<=b;i++){ //for ith element boolean flag = true; for(int j=2;j<=(int)java.lang.Math.pow(i,0.5);j++){ if(i%j==0){ flag=false; } } if(flag==true){ count++; } } list.add(count); t–; } for(int i=0;i<list.size();i++){ System.out.println(list.get(i)); } } }

#6

Hi Vaibhav,
This question has to be done through sieve method.

#7

Hi @Vaibhav-Garg-1998823966894298
As you are not responding to this thread, I am marking your doubt as Resolved for now. Re-open it if required.

Please mark your doubts as resolved in your course’s “ Ask Doubt ” section, when your doubt is resolved.