10533  Digit Primes
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10533  Digit Primes
Could anyone tell me what is the answer for this input?
1 1000000
I've got 30123 but I've got WA ....
Best regards
DM
1 1000000
I've got 30123 but I've got WA ....
Best regards
DM
If you really want to get Accepted, try to think about possible, and after that  about impossible ... and you'll get, what you want ....
Born from ashes  restarting counter of problems (800+ solved problems)
Born from ashes  restarting counter of problems (800+ solved problems)

 Experienced poster
 Posts: 187
 Joined: Wed Dec 11, 2002 2:03 pm
 Location: Mount Papandayan, Garut
i think there is no input like that, maximum is 999999
try this input :
output should be : (according to my ACC prog)
hope this helps.
regards,
titid
try this input :
Code: Select all
5
1 999999
11 11
10 10
11 20
11 29
Code: Select all
30123
1
0
1
3
regards,
titid
Kalo mau kaya, buat apa sekolah?

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titid, I got the same results .... as you ...
hmmm I don't know what can I do wrong ...
Could I send you my code ?
anapum: use DP
Best regards
DM
hmmm I don't know what can I do wrong ...
Could I send you my code ?
anapum: use DP
Best regards
DM
If you really want to get Accepted, try to think about possible, and after that  about impossible ... and you'll get, what you want ....
Born from ashes  restarting counter of problems (800+ solved problems)
Born from ashes  restarting counter of problems (800+ solved problems)

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 Posts: 8
 Joined: Thu Jul 31, 2003 2:36 pm

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I don't think so ... I don't consider such case and in problem description is sentence which clearly tell us, that first number is not greater than second ....
Best regards
DM
Best regards
DM
If you really want to get Accepted, try to think about possible, and after that  about impossible ... and you'll get, what you want ....
Born from ashes  restarting counter of problems (800+ solved problems)
Born from ashes  restarting counter of problems (800+ solved problems)

 New poster
 Posts: 16
 Joined: Mon Jan 06, 2003 9:27 pm
 Location: Grosskrut, Austria
Dear Faizur,
A few hints for an efficient solution of Shahriar’s problem „Digit Primes“ (10533). I’ve just started working on the program ... these are the major parts of my „design“:
1.)
To count the number of „Digit Primes“ within the range [t1, t2] means to first check if the number is prime and then to check the digit sum being prime (which is the „weaker sieve“). For both activities You need a look up table of the prime numbers up to t2 which can be produced by using the „sieve of Eratosthenes“. Note that you only have to strike out the multiples of the primes up to sqrt(t2) to get the complete look up table of all prime numbers up to t2. I think performing this once for a t2_max=999999 should be fine for this problem.
2.)
You should also use an efficient algorithm to calculate the digit sum – try this one:
[c]int digit_sum(int number)
{ int sum = 0;
do
{
sum += number;
number /= 10;
sum = number*10;
} while (number);
return sum;
}[/c]
3.)
Perhaps some of the input case ranges overlap and performing some bookkeeping for reusing ranges which have already been checked might pay off.
Yours, Eric
A few hints for an efficient solution of Shahriar’s problem „Digit Primes“ (10533). I’ve just started working on the program ... these are the major parts of my „design“:
1.)
To count the number of „Digit Primes“ within the range [t1, t2] means to first check if the number is prime and then to check the digit sum being prime (which is the „weaker sieve“). For both activities You need a look up table of the prime numbers up to t2 which can be produced by using the „sieve of Eratosthenes“. Note that you only have to strike out the multiples of the primes up to sqrt(t2) to get the complete look up table of all prime numbers up to t2. I think performing this once for a t2_max=999999 should be fine for this problem.
2.)
You should also use an efficient algorithm to calculate the digit sum – try this one:
[c]int digit_sum(int number)
{ int sum = 0;
do
{
sum += number;
number /= 10;
sum = number*10;
} while (number);
return sum;
}[/c]
3.)
Perhaps some of the input case ranges overlap and performing some bookkeeping for reusing ranges which have already been checked might pay off.
Yours, Eric

 New poster
 Posts: 16
 Joined: Mon Jan 06, 2003 9:27 pm
 Location: Grosskrut, Austria
Sorry folks,
I have to revise my own posting after a few learning cycles with TLE. I finally got AC (1.664 seconds). Here some new (and better) hints:
A.) Forget the algorithm for calculating the digit sum! When going up through the odd numbers (3,5,7, ...) and checking for digit primes you can keep track of the digit sum in parallel.
B.) The look up table containing TRUE for digit primes and FALSE for the rest has to be "integrated" (once) to prevent having to loop from t1 to t2 for each input case. This can be done in parallel with the loop in (A) and then the number of digit primes is generally the expression:
(integrated_list[t2]  integrated_list[t11])
... where integrated_list[] is an array starting with the counter value 0 and incrementing at each index of a digit prime.
Yours, Eric
I have to revise my own posting after a few learning cycles with TLE. I finally got AC (1.664 seconds). Here some new (and better) hints:
A.) Forget the algorithm for calculating the digit sum! When going up through the odd numbers (3,5,7, ...) and checking for digit primes you can keep track of the digit sum in parallel.
B.) The look up table containing TRUE for digit primes and FALSE for the rest has to be "integrated" (once) to prevent having to loop from t1 to t2 for each input case. This can be done in parallel with the loop in (A) and then the number of digit primes is generally the expression:
(integrated_list[t2]  integrated_list[t11])
... where integrated_list[] is an array starting with the counter value 0 and incrementing at each index of a digit prime.
Yours, Eric
Can you guys tell me, why on earth this program gets RTE(Floating point Exception)...I am totally depressed seeing this message again & again...
please someone help me out...
At last I got AC...I had to change my prime generating function...
thanks guys
Razib
please someone help me out...
At last I got AC...I had to change my prime generating function...
thanks guys
Code: Select all
Deleted
Last edited by razibcse on Mon Oct 20, 2003 2:52 pm, edited 1 time in total.
Wisdom is know what to do next; virtue is doing it.

 New poster
 Posts: 16
 Joined: Mon Jan 06, 2003 9:27 pm
 Location: Grosskrut, Austria

 Guru
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Cound anyone help with my code? ><"
I try many cases, but still can't find the problem.
I try many cases, but still can't find the problem.
Code: Select all
#include<stdio.h>
typedef struct {
int digitprimestate;
long key;
}NUM;
NUM array[1000002];
int primestate[1000002];
long getdigitnum(long n);
int main()
{
long digitprimecount = 2;
long cases;
long left,right;
long i,j;
primestate[1] = 0;
array[1].digitprimestate = 0;
array[1].key = 0;
primestate[2] = 1;
array[2].digitprimestate = 1;
array[2].key = 1;
primestate[3] = 1;
array[3].digitprimestate = 1;
array[3].key = 2;
primestate[4] = 0;
array[4].digitprimestate = 0;
array[4].key = 2;
for(i=5;i<1000000;i+=2){
for(j=3;j*j<=i;j+=2)
if(i%j==0) break;
if(i%j!=0){
primestate[i]=1;
if( primestate[ getdigitnum(i) ] == 1 ){
array[i].digitprimestate = 1;
array[i].key = ++digitprimecount;
}
}
else{
array[i].digitprimestate = 0;
array[i].key = digitprimecount;
}
array[i+1].digitprimestate = 0;
array[i+1].key = digitprimecount;
}
scanf("%ld",&cases);
while(cases>0){
scanf("%ld %ld",&left,&right);
printf("%ld\n",array[right].key  array[left1].key);
}
return 0;
}
long getdigitnum(long n){
long a=0;
for(;n;n/=10)
a+=n%10;
return a;
}