Mixing
Giving right answer for N = 2000000 but not passing test cases
0
Find the sum of all prime numbers not greater than N. For example if user input 5 then prime numbers are 2,3,5 and their sum is 10. It is not passing 4 test cases in which two of them are exceeding the time limit. I have tried several test cases and my code is working fine on them. Here is my code.
public static long sieve_of_eratosthenes(long n)
{
if (n == 1)
{
// If the user input 1.
return (0);
}
else
{
long sum = 0;
bool array = new bool[n + 1];
for (long i = 2; i <= n; i++)
{
// Setting all values to true.
array[i] = true;
}
// Eliminating the composite numbers.
for (long j = 2; j < Math.Sqrt(n); j++)
{
if (array[j])
{
long multiple = 1;
for (long k = (j * j); k <= n; k = (j * j) + (j * (multiple++)))
{
array[k] = false;
}
}
}
//Now we have the prime numbers. We just have to add them.
for (int z = 2; z <= n; z++)
{
if (array[z])
{
sum = sum + z;
}
}
return (sum);
}
}
static void Main(string args)
{
int noofcases = int.Parse(Console.ReadLine());
for( int i = 0; i < noofcases; i ++)
{
long entry = long.Parse(Console.ReadLine());
Console.WriteLine(sieve_of_eratosthenes(entry));
}
}
c#
edited Jan 1 at 15:19
Sentry
3,69822234
asked Jan 1 at 15:10
Riven CallahanRiven Callahan
85
|
show 1 more comment
0
Find the sum of all prime numbers not greater than N. For example if user input 5 then prime numbers are 2,3,5 and their sum is 10. It is not passing 4 test cases in which two of them are exceeding the time limit. I have tried several test cases and my code is working fine on them. Here is my code.
public static long sieve_of_eratosthenes(long n)
{
if (n == 1)
{
// If the user input 1.
return (0);
}
else
{
long sum = 0;
bool array = new bool[n + 1];
for (long i = 2; i <= n; i++)
{
// Setting all values to true.
array[i] = true;
}
// Eliminating the composite numbers.
for (long j = 2; j < Math.Sqrt(n); j++)
{
if (array[j])
{
long multiple = 1;
for (long k = (j * j); k <= n; k = (j * j) + (j * (multiple++)))
{
array[k] = false;
}
}
}
//Now we have the prime numbers. We just have to add them.
for (int z = 2; z <= n; z++)
{
if (array[z])
{
sum = sum + z;
}
}
return (sum);
}
}
static void Main(string args)
{
int noofcases = int.Parse(Console.ReadLine());
for( int i = 0; i < noofcases; i ++)
{
long entry = long.Parse(Console.ReadLine());
Console.WriteLine(sieve_of_eratosthenes(entry));
}
}
c#
edited Jan 1 at 15:19
Sentry
3,69822234
asked Jan 1 at 15:10
Riven CallahanRiven Callahan
85
Your logic might work, but it is far from efficient. The usage of arrays is unnecessary here, just do the check for a prime-number in a for-loop and calculate the sum while doing it instead of using such huge arrays to store your results inbetween. This clogs your memory and massively hurts your performance.
– Compufreak
Jan 1 at 15:22
i only find Sieve's method for finding the prime numbers that's why i use arrays. can you please elaborate the method you are talking about.
– Riven Callahan
Jan 1 at 15:39
I suspect there is a rounding issue with the SQRT method : j < Math.Sqrt(n) Try rounding up using Celing method.
– jdweng
Jan 1 at 15:41
It didn't make any difference in the outcome. @jdweng
– Riven Callahan
Jan 1 at 15:49
You can speed up algorithm by eliminating all even numbers except 2. : int z = 3; z <= n; z += 2 and long j = 3; j < Math.Sqrt(n); j += 2
– jdweng
Jan 1 at 16:03
|
show 1 more comment
0
0
0
Find the sum of all prime numbers not greater than N. For example if user input 5 then prime numbers are 2,3,5 and their sum is 10. It is not passing 4 test cases in which two of them are exceeding the time limit. I have tried several test cases and my code is working fine on them. Here is my code.
public static long sieve_of_eratosthenes(long n)
{
if (n == 1)
{
// If the user input 1.
return (0);
}
else
{
long sum = 0;
bool array = new bool[n + 1];
for (long i = 2; i <= n; i++)
{
// Setting all values to true.
array[i] = true;
}
// Eliminating the composite numbers.
for (long j = 2; j < Math.Sqrt(n); j++)
{
if (array[j])
{
long multiple = 1;
for (long k = (j * j); k <= n; k = (j * j) + (j * (multiple++)))
{
array[k] = false;
}
}
}
//Now we have the prime numbers. We just have to add them.
for (int z = 2; z <= n; z++)
{
if (array[z])
{
sum = sum + z;
}
}
return (sum);
}
}
static void Main(string args)
{
int noofcases = int.Parse(Console.ReadLine());
for( int i = 0; i < noofcases; i ++)
{
long entry = long.Parse(Console.ReadLine());
Console.WriteLine(sieve_of_eratosthenes(entry));
}
}
c#
edited Jan 1 at 15:19
Sentry
3,69822234
asked Jan 1 at 15:10
Riven CallahanRiven Callahan
85
Find the sum of all prime numbers not greater than N. For example if user input 5 then prime numbers are 2,3,5 and their sum is 10. It is not passing 4 test cases in which two of them are exceeding the time limit. I have tried several test cases and my code is working fine on them. Here is my code.
public static long sieve_of_eratosthenes(long n)
{
if (n == 1)
{
// If the user input 1.
return (0);
}
else
{
long sum = 0;
bool array = new bool[n + 1];
for (long i = 2; i <= n; i++)
{
// Setting all values to true.
array[i] = true;
}
// Eliminating the composite numbers.
for (long j = 2; j < Math.Sqrt(n); j++)
{
if (array[j])
{
long multiple = 1;
for (long k = (j * j); k <= n; k = (j * j) + (j * (multiple++)))
{
array[k] = false;
}
}
}
//Now we have the prime numbers. We just have to add them.
for (int z = 2; z <= n; z++)
{
if (array[z])
{
sum = sum + z;
}
}
return (sum);
}
}
static void Main(string args)
{
int noofcases = int.Parse(Console.ReadLine());
for( int i = 0; i < noofcases; i ++)
{
long entry = long.Parse(Console.ReadLine());
Console.WriteLine(sieve_of_eratosthenes(entry));
}
}
c#
c#
edited Jan 1 at 15:19
Sentry
3,69822234
asked Jan 1 at 15:10
Riven CallahanRiven Callahan
85
edited Jan 1 at 15:19
Sentry
3,69822234
asked Jan 1 at 15:10
Riven CallahanRiven Callahan
85
edited Jan 1 at 15:19
Sentry
3,69822234
edited Jan 1 at 15:19
Sentry
3,69822234
edited Jan 1 at 15:19
Sentry
3,69822234
3,69822234
asked Jan 1 at 15:10
Riven CallahanRiven Callahan
85
asked Jan 1 at 15:10
Riven CallahanRiven Callahan
85
asked Jan 1 at 15:10
Riven CallahanRiven Callahan
85
85
Your logic might work, but it is far from efficient. The usage of arrays is unnecessary here, just do the check for a prime-number in a for-loop and calculate the sum while doing it instead of using such huge arrays to store your results inbetween. This clogs your memory and massively hurts your performance.
– Compufreak
Jan 1 at 15:22
i only find Sieve's method for finding the prime numbers that's why i use arrays. can you please elaborate the method you are talking about.
– Riven Callahan
Jan 1 at 15:39
I suspect there is a rounding issue with the SQRT method : j < Math.Sqrt(n) Try rounding up using Celing method.
– jdweng
Jan 1 at 15:41
It didn't make any difference in the outcome. @jdweng
– Riven Callahan
Jan 1 at 15:49
You can speed up algorithm by eliminating all even numbers except 2. : int z = 3; z <= n; z += 2 and long j = 3; j < Math.Sqrt(n); j += 2
– jdweng
Jan 1 at 16:03
|
show 1 more comment
Your logic might work, but it is far from efficient. The usage of arrays is unnecessary here, just do the check for a prime-number in a for-loop and calculate the sum while doing it instead of using such huge arrays to store your results inbetween. This clogs your memory and massively hurts your performance.
– Compufreak
Jan 1 at 15:22
i only find Sieve's method for finding the prime numbers that's why i use arrays. can you please elaborate the method you are talking about.
– Riven Callahan
Jan 1 at 15:39
I suspect there is a rounding issue with the SQRT method : j < Math.Sqrt(n) Try rounding up using Celing method.
– jdweng
Jan 1 at 15:41
It didn't make any difference in the outcome. @jdweng
– Riven Callahan
Jan 1 at 15:49
You can speed up algorithm by eliminating all even numbers except 2. : int z = 3; z <= n; z += 2 and long j = 3; j < Math.Sqrt(n); j += 2
– jdweng
Jan 1 at 16:03
Your logic might work, but it is far from efficient. The usage of arrays is unnecessary here, just do the check for a prime-number in a for-loop and calculate the sum while doing it instead of using such huge arrays to store your results inbetween. This clogs your memory and massively hurts your performance.
– Compufreak
Jan 1 at 15:22
Your logic might work, but it is far from efficient. The usage of arrays is unnecessary here, just do the check for a prime-number in a for-loop and calculate the sum while doing it instead of using such huge arrays to store your results inbetween. This clogs your memory and massively hurts your performance.
– Compufreak
Jan 1 at 15:22
i only find Sieve's method for finding the prime numbers that's why i use arrays. can you please elaborate the method you are talking about.
– Riven Callahan
Jan 1 at 15:39
i only find Sieve's method for finding the prime numbers that's why i use arrays. can you please elaborate the method you are talking about.
– Riven Callahan
Jan 1 at 15:39
I suspect there is a rounding issue with the SQRT method : j < Math.Sqrt(n) Try rounding up using Celing method.
– jdweng
Jan 1 at 15:41
I suspect there is a rounding issue with the SQRT method : j < Math.Sqrt(n) Try rounding up using Celing method.
– jdweng
Jan 1 at 15:41
It didn't make any difference in the outcome. @jdweng
– Riven Callahan
Jan 1 at 15:49
It didn't make any difference in the outcome. @jdweng
– Riven Callahan
Jan 1 at 15:49
You can speed up algorithm by eliminating all even numbers except 2. : int z = 3; z <= n; z += 2 and long j = 3; j < Math.Sqrt(n); j += 2
– jdweng
Jan 1 at 16:03
You can speed up algorithm by eliminating all even numbers except 2. : int z = 3; z <= n; z += 2 and long j = 3; j < Math.Sqrt(n); j += 2
– jdweng
Jan 1 at 16:03
|
show 1 more comment
1 Answer
1
active
oldest
votes
2
check the below code. I wrote simple logic which you can improve
public static class Int32Extension
{
public static bool IsPrime(this int number)
{
if (number <= 1) return false;
if (number == 2) return true;
if (number % 2 == 0) return false;
var boundary = (int)Math.Floor(Math.Sqrt(number));
for (int i = 3; i <= boundary; i += 2)
if (number % i == 0)
return false;
return true;
}
}
then
static void Main(string args)
{
int input = 5;
int sum = 0;
for (int i = 0; i < input;)
{
if (!(++i).IsPrime())
continue;
sum += i;
}
Console.WriteLine(sum);
}
Without using Extension Method
public static bool IsPrime(int number)
{
if (number <= 1) return false;
if (number == 2) return true;
if (number % 2 == 0) return false;
var boundary = (int)Math.Floor(Math.Sqrt(number));
for (int i = 3; i <= boundary; i += 2)
if (number % i == 0)
return false;
return true;
}
static void Main(string args)
{
int input = 5;
int sum = 0;
for (int i = 0; i < input;)
{
if (!IsPrime(++i))
continue;
sum += i;
}
Console.WriteLine(sum);
}
.Net Fiddle Link : https://dotnetfiddle.net/rEBY9r
Edit : The IsPrime test uses Primality Test With Pseudocode
answered Jan 1 at 15:30
SimonareSimonare
15.1k11840
Thanks for helping, it looks like good code, but I feel it's probably not what the Op needs. It uses advanced language features like extensions and it doesn't help him to learn the basics. See How do I ask and answer homework questions
– Compufreak
Jan 1 at 15:34
thanks for the answer. but can you tell me the logic of the boundary variable. i will be very thankful for yours.
– Riven Callahan
Jan 1 at 15:38
check the included reference
– Simonare
Jan 1 at 15:47
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
2
check the below code. I wrote simple logic which you can improve
public static class Int32Extension
{
public static bool IsPrime(this int number)
{
if (number <= 1) return false;
if (number == 2) return true;
if (number % 2 == 0) return false;
var boundary = (int)Math.Floor(Math.Sqrt(number));
for (int i = 3; i <= boundary; i += 2)
if (number % i == 0)
return false;
return true;
}
}
then
static void Main(string args)
{
int input = 5;
int sum = 0;
for (int i = 0; i < input;)
{
if (!(++i).IsPrime())
continue;
sum += i;
}
Console.WriteLine(sum);
}
Without using Extension Method
public static bool IsPrime(int number)
{
if (number <= 1) return false;
if (number == 2) return true;
if (number % 2 == 0) return false;
var boundary = (int)Math.Floor(Math.Sqrt(number));
for (int i = 3; i <= boundary; i += 2)
if (number % i == 0)
return false;
return true;
}
static void Main(string args)
{
int input = 5;
int sum = 0;
for (int i = 0; i < input;)
{
if (!IsPrime(++i))
continue;
sum += i;
}
Console.WriteLine(sum);
}
.Net Fiddle Link : https://dotnetfiddle.net/rEBY9r
Edit : The IsPrime test uses Primality Test With Pseudocode
answered Jan 1 at 15:30
SimonareSimonare
15.1k11840
Thanks for helping, it looks like good code, but I feel it's probably not what the Op needs. It uses advanced language features like extensions and it doesn't help him to learn the basics. See How do I ask and answer homework questions
– Compufreak
Jan 1 at 15:34
thanks for the answer. but can you tell me the logic of the boundary variable. i will be very thankful for yours.
– Riven Callahan
Jan 1 at 15:38
check the included reference
– Simonare
Jan 1 at 15:47
add a comment |
2
check the below code. I wrote simple logic which you can improve
public static class Int32Extension
{
public static bool IsPrime(this int number)
{
if (number <= 1) return false;
if (number == 2) return true;
if (number % 2 == 0) return false;
var boundary = (int)Math.Floor(Math.Sqrt(number));
for (int i = 3; i <= boundary; i += 2)
if (number % i == 0)
return false;
return true;
}
}
then
static void Main(string args)
{
int input = 5;
int sum = 0;
for (int i = 0; i < input;)
{
if (!(++i).IsPrime())
continue;
sum += i;
}
Console.WriteLine(sum);
}
Without using Extension Method
public static bool IsPrime(int number)
{
if (number <= 1) return false;
if (number == 2) return true;
if (number % 2 == 0) return false;
var boundary = (int)Math.Floor(Math.Sqrt(number));
for (int i = 3; i <= boundary; i += 2)
if (number % i == 0)
return false;
return true;
}
static void Main(string args)
{
int input = 5;
int sum = 0;
for (int i = 0; i < input;)
{
if (!IsPrime(++i))
continue;
sum += i;
}
Console.WriteLine(sum);
}
.Net Fiddle Link : https://dotnetfiddle.net/rEBY9r
Edit : The IsPrime test uses Primality Test With Pseudocode
answered Jan 1 at 15:30
SimonareSimonare
15.1k11840
Thanks for helping, it looks like good code, but I feel it's probably not what the Op needs. It uses advanced language features like extensions and it doesn't help him to learn the basics. See How do I ask and answer homework questions
– Compufreak
Jan 1 at 15:34
thanks for the answer. but can you tell me the logic of the boundary variable. i will be very thankful for yours.
– Riven Callahan
Jan 1 at 15:38
check the included reference
– Simonare
Jan 1 at 15:47
add a comment |
2
2
2
check the below code. I wrote simple logic which you can improve
public static class Int32Extension
{
public static bool IsPrime(this int number)
{
if (number <= 1) return false;
if (number == 2) return true;
if (number % 2 == 0) return false;
var boundary = (int)Math.Floor(Math.Sqrt(number));
for (int i = 3; i <= boundary; i += 2)
if (number % i == 0)
return false;
return true;
}
}
then
static void Main(string args)
{
int input = 5;
int sum = 0;
for (int i = 0; i < input;)
{
if (!(++i).IsPrime())
continue;
sum += i;
}
Console.WriteLine(sum);
}
Without using Extension Method
public static bool IsPrime(int number)
{
if (number <= 1) return false;
if (number == 2) return true;
if (number % 2 == 0) return false;
var boundary = (int)Math.Floor(Math.Sqrt(number));
for (int i = 3; i <= boundary; i += 2)
if (number % i == 0)
return false;
return true;
}
static void Main(string args)
{
int input = 5;
int sum = 0;
for (int i = 0; i < input;)
{
if (!IsPrime(++i))
continue;
sum += i;
}
Console.WriteLine(sum);
}
.Net Fiddle Link : https://dotnetfiddle.net/rEBY9r
Edit : The IsPrime test uses Primality Test With Pseudocode
answered Jan 1 at 15:30
SimonareSimonare
15.1k11840
check the below code. I wrote simple logic which you can improve
public static class Int32Extension
{
public static bool IsPrime(this int number)
{
if (number <= 1) return false;
if (number == 2) return true;
if (number % 2 == 0) return false;
var boundary = (int)Math.Floor(Math.Sqrt(number));
for (int i = 3; i <= boundary; i += 2)
if (number % i == 0)
return false;
return true;
}
}
then
static void Main(string args)
{
int input = 5;
int sum = 0;
for (int i = 0; i < input;)
{
if (!(++i).IsPrime())
continue;
sum += i;
}
Console.WriteLine(sum);
}
Without using Extension Method
public static bool IsPrime(int number)
{
if (number <= 1) return false;
if (number == 2) return true;
if (number % 2 == 0) return false;
var boundary = (int)Math.Floor(Math.Sqrt(number));
for (int i = 3; i <= boundary; i += 2)
if (number % i == 0)
return false;
return true;
}
static void Main(string args)
{
int input = 5;
int sum = 0;
for (int i = 0; i < input;)
{
if (!IsPrime(++i))
continue;
sum += i;
}
Console.WriteLine(sum);
}
.Net Fiddle Link : https://dotnetfiddle.net/rEBY9r
Edit : The IsPrime test uses Primality Test With Pseudocode
answered Jan 1 at 15:30
SimonareSimonare
15.1k11840
edited Jan 1 at 15:59
answered Jan 1 at 15:30
SimonareSimonare
15.1k11840
answered Jan 1 at 15:30
SimonareSimonare
15.1k11840
answered Jan 1 at 15:30
SimonareSimonare
15.1k11840
15.1k11840
Thanks for helping, it looks like good code, but I feel it's probably not what the Op needs. It uses advanced language features like extensions and it doesn't help him to learn the basics. See How do I ask and answer homework questions
– Compufreak
Jan 1 at 15:34
thanks for the answer. but can you tell me the logic of the boundary variable. i will be very thankful for yours.
– Riven Callahan
Jan 1 at 15:38
check the included reference
– Simonare
Jan 1 at 15:47
add a comment |
Thanks for helping, it looks like good code, but I feel it's probably not what the Op needs. It uses advanced language features like extensions and it doesn't help him to learn the basics. See How do I ask and answer homework questions
– Compufreak
Jan 1 at 15:34
thanks for the answer. but can you tell me the logic of the boundary variable. i will be very thankful for yours.
– Riven Callahan
Jan 1 at 15:38
check the included reference
– Simonare
Jan 1 at 15:47
Thanks for helping, it looks like good code, but I feel it's probably not what the Op needs. It uses advanced language features like extensions and it doesn't help him to learn the basics. See How do I ask and answer homework questions
– Compufreak
Jan 1 at 15:34
Thanks for helping, it looks like good code, but I feel it's probably not what the Op needs. It uses advanced language features like extensions and it doesn't help him to learn the basics. See How do I ask and answer homework questions
– Compufreak
Jan 1 at 15:34
thanks for the answer. but can you tell me the logic of the boundary variable. i will be very thankful for yours.
– Riven Callahan
Jan 1 at 15:38
thanks for the answer. but can you tell me the logic of the boundary variable. i will be very thankful for yours.
– Riven Callahan
Jan 1 at 15:38
check the included reference
– Simonare
Jan 1 at 15:47
check the included reference
– Simonare
Jan 1 at 15:47
add a comment |
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Your logic might work, but it is far from efficient. The usage of arrays is unnecessary here, just do the check for a prime-number in a for-loop and calculate the sum while doing it instead of using such huge arrays to store your results inbetween. This clogs your memory and massively hurts your performance.
– Compufreak
Jan 1 at 15:22
i only find Sieve's method for finding the prime numbers that's why i use arrays. can you please elaborate the method you are talking about.
– Riven Callahan
Jan 1 at 15:39
I suspect there is a rounding issue with the SQRT method : j < Math.Sqrt(n) Try rounding up using Celing method.
– jdweng
Jan 1 at 15:41
It didn't make any difference in the outcome. @jdweng
– Riven Callahan
Jan 1 at 15:49
You can speed up algorithm by eliminating all even numbers except 2. : int z = 3; z <= n; z += 2 and long j = 3; j < Math.Sqrt(n); j += 2
– jdweng
Jan 1 at 16:03