## 10533 - Digit Primes

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Eduard
Experienced poster
Posts: 183
Joined: Fri Sep 26, 2003 2:54 pm
Location: Armenia,Yerevan

### 10533

help please my program works fast and correct on my computer but gives WA. help pleas.[pascal]program acm10533;
var i,j,a,b,number,p,k,i1:longint;
c:array[0..1000000] of longint;
l:boolean;
procedure parz(n:longint;var h:boolean);
label 1;
var i:integer;
begin
h:=true;
for i:=2 to trunc(sqrt(n)) do
if n mod i=0 then begin h:=false;goto 1;end;
1:
end;
begin
c[0]:=0;
for i:=1 to 1000000 do
begin
k:=0;
i1:=i;
parz(i,l);
if l=true then
begin
repeat
k:=k+(i mod 10);
i:=i div 10;
until i=0;
i:=i1;
parz(k,l);
if l=true then c:=c[i-1]+1 else c:=c[i-1];
end else c:=c[i-1];
end;
for p:=1 to number do
begin
writeln(c-c[a]);
end;
end.
[/pascal]
someone who like to solve informatic problems.
http://acm.uva.es/cgi-bin/OnlineJudge?AuthorInfo:29650

sohel
Guru
Posts: 856
Joined: Thu Jan 30, 2003 5:50 am
Location: New York

### Critical Inputs

Hi Eduard,
I am not an expert in interpreting PASCAL code, but here is some critical inputs.

What is your output for the following cases:

10
5 8
1 999999
11 25
3 3
5 6
6 7
1 100
9 10
200 300
12 13

Eduard
Experienced poster
Posts: 183
Joined: Fri Sep 26, 2003 2:54 pm
Location: Armenia,Yerevan

1
30123
1
1
0
1
14
0
8
0
someone who like to solve informatic problems.
http://acm.uva.es/cgi-bin/OnlineJudge?AuthorInfo:29650

osan
New poster
Posts: 47
Joined: Tue Jul 29, 2003 12:03 pm
Contact:

### REAL OUTPUT FOR THOSE INPUT

INPUT
11
5 8
1 999999
11 25
3 3
5 6
6 7
1 100
9 10
200 300
12 13
1 10

OUTPUT
2
56
2
1
1
1
14
0
8
0
4
this time WA
what next...............?

pavelph
Learning poster
Posts: 57
Joined: Wed Dec 10, 2003 7:32 pm
Location: Russia, Saint-Petersburg

### TLE :(

Hi! I have TLE on this problem, but I don't know how I can make my program faster.
I have algo that:
1) get_primes_numbers (Eratosphean)
2) get_digit_primes_numbers
It makes

Code: Select all

``d: array [1 .. 1000000] of boolean``
and d=true if i - digit prime. And this two procedures works <1 sec. !!!
It means that very slow work procedure that count how many 'true' values in array from t1 to t2. Help me please, how I can optimise this procedure:
for i:=1 to n do begin
counter:=0;
if not odd(n1) then inc(n1);
while n1<=n2 do begin
if d[n1] then inc(counter);
inc(n1, 2);
end;
writeln(counter);
end;
[/pascal]

UFP2161
A great helper
Posts: 277
Joined: Mon Jul 21, 2003 7:49 pm
Contact:
Have you ever considered a second lookup table that consists of the number of digit primes less than or equal to the index?

No point in repeating boolean checks for 1...999999, then 1...999998, then 1...999997, etc.

Just do it once, and extrapolate the answer given the range.

pavelph
Learning poster
Posts: 57
Joined: Wed Dec 10, 2003 7:32 pm
Location: Russia, Saint-Petersburg
Oh, yes, of course It's really very easy.
Thank you very much, now I have got AC on 10533 in 5 sec.

soyoja
Experienced poster
Posts: 106
Joined: Sun Feb 17, 2002 2:00 am
Location: Seoul, South Korea
Contact:
First time, I tried to find amount of digit prime to use binary search...

( Using index of digit prime stored array )

But there are some problems...

( Binary search has some problem when an index value has no

digit prime, and so on... )

So I use 1,000,000 size integer array

and accumulate all digit prime, and range value to calculate

accumulated array.

P.S ) When I use Visual C++, I can only set 250,000 size integer

array. So I use gcc, and I can declare one million size int array.

playerX
Learning poster
Posts: 63
Joined: Fri Apr 25, 2003 11:57 pm
Location: Coimbra, Portugal
i'm having wa... probably a small mistake, i'll look at it more attentively
be cool...

Kamanashish
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Location: Dhaka
Contact:

### 10533 - Digit Primes

I can not understand what is the wrong with it.Have there any critical input?

//Cutted
Last edited by Kamanashish on Tue Jun 15, 2004 4:14 pm, edited 1 time in total.
Work hard.

Rajib
New poster
Posts: 28
Joined: Tue Nov 04, 2003 6:45 am
if(a[l]=='1')c++;
Do you think this portion will work correct...

13 is a prime number but not a digit prime. But in that protion you increase c by one (c++) if lower bound (l) is prime only. You must test whether (l) is a digit prime...

Test these:

Input:
3
3 5
13 13
11 13
Output:
2
0
1
Goodluck...
All the part of your code seem correct. Cut the code if you get AC.

Kamanashish
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Posts: 10
Joined: Wed Dec 17, 2003 3:12 pm
Location: Dhaka
Contact:
Thanks Rajib. At last i have got AC.
Work hard.

jahangirk
New poster
Posts: 5
Joined: Sat Jun 26, 2004 11:15 pm

### 10533. Digit prime . Why TLE .. Somebody help me plzzzzz

i m getting time limit exceed . plz help me i dont know y

[cpp]

#include<stdio.h>

bool checkprime(int num)
{
int flag=0;

if(num==2)
{
return true;
}
else
{
int count=2;
while(count<=(num/2)+1)
{
flag = 0;
if((num%count)==0)
{
flag=1;
break;
}
count=count+1;
}
if(flag!=1)
{
return true;
}
return false;
}

}

int main()
{
bool v;
int lim;
int i;

scanf("%d",&lim);

int upper,lower;

for(int k=0;k<lim;k++)
{
int total=0;

scanf("%d",&lower);
scanf("%d",&upper);

for(i=lower;i<upper;i++)
{

v=checkprime(i);

if(v==true)
{

int sum=0;

if(i>10)
{
int n=i;
int rem;

while(n>=10)
{
rem=n%10;
n=n/10;

sum=sum+rem;
}
sum=sum+n;

if(checkprime(sum))
{
total=total+1;
}

}

}
else
{
if(checkprime(i))
{
total=total+1;
}
}

}
printf("%d",total);
printf("\n");
}
return 0;
}

[/cpp]

shamim
A great helper
Posts: 498
Joined: Mon Dec 30, 2002 10:10 am
Location: Bozeman, Montana, USA
Your prime testing method is highly inefficient. There are posts that has efficient method to test prime.

Sanny
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Posts: 78
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Contact:
Hi,
Besides the efficiency of ur prime testing function, there are other things u should look at.
As the number of test cases is 500000, u must use dynamic programming here.
And u better use the sieve method to generate all the primes.