Hello Buddy,
as per the test case(sample input and output) i wrote the code but in one test case i got TLE, please help me whats issue in this please.
Prime Visits ISSUR
@s.v,
You are supposed to use the prime seive optimisation technique. Also make sure that you call the primeseive function that you will make before the test cases only to prevent TLE.
Precompute the prime numbers using sieve technique.
In the sieve technique where you create a boolean array of 1000005 size.
And start from the first prime number i.e. 2. Take its square(4) and increment it by the number you took (i.e. 4,6,8,10 and so on). Mark all these as false since they cannot be primes.
Now take the next unmarked number, 3. And mark 9,12,15 and so as false. Similarly do it for 4. 16,20,24 and so on as false.
When you finish the loop, count the number of primes within the range.
Further explained:
In the image below, say we have to get all primes between 1-100. First outside the loop mark 1 as not a prime number (in case of boolean array as true or in int array as 1).
Now enter a for loop:
find the index which has set value as 0. initially it will be 2.
Start another for loop and mark all the numbers which are divisible by 2 and are greater than or equal to the square of it as true/1 (not primes). these numbers will be 4,6,8,10 and so on.
Now the next number will be 3. these numbers will be 9,12,15 and so on.
Similarly do it till 10 if total numbers are 100.
After this do a simple traversal to store all the prime numbers. Refer to the image below for a visualization
@s.v,
Buddy, calculate the prime numbers before. For every sub test case, you need not calculate the prime numbers again and again.
can you tell me where its going wrong?
@s.v,
public static void main(String[] args) {
int value=0, num=0, size;
size = sc.nextInt();
for(int l=0; l<size;l++){
value = sc.nextInt();
num = sc.nextInt();
int sol = seive(value,num);
System.out.println(sol);
}
}
In this, for every input of value and num you are calculating prime numbers. Instead, calculate prime numbers only once (outside the for loop) till 1000005 and then simply count prime numbers between num and value to get your answer
How can i comes out from loop, i didn’t understand where to break/comes out.