## 11151 - Longest Palindrome

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soyoja
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### 11151 - Longest Palindrome

hmm.. It's so tricky. It just looks like an easy problem, but I received WA repeatedly... Is there any critical input?
I love Problem Solving!!!

emotional blind
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### Re: 11151 Longest Palindrome

soyoja wrote:Is there any critical input?
My code takes emtpy string as input.

Karim
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### 11151 WA

I am getting wrong answer but i dont know why

can anyone tell me

Here is the code

#include<iostream>
#include<string>
#include<algorithm>
using namespace std;

string s,t1,t2;

int main()
{
//freopen("d.in","rt",stdin);
int t;
int i,j;

cin>>t;
getline(cin,s);
for(i=0;i<t;i++)
{
getline(cin,s);
if(s=="")
{
cout<<"0"<<endl;
continue;
}
for(j=0;j<s.length();j++)
{
t1 = s.substr(0,s.length()-j);
t2 = s.substr(0,s.length()-j);
reverse( t1.begin() , t1.end() );
if(t1 == t2)
{
cout<<t1.length()<<endl;
break;
}
t1 = s.substr(j);
t2 = s.substr(j);
reverse( t1.begin() , t1.end() );
if(t1 == t2 )
{
cout<<t1.length()<<endl;
break;
}
}
}
return 0;
}

jan_holmes
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Posts: 136
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Location: Singapore
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Try this input :

Code: Select all

``````
1

``````
I think the output should be :

Code: Select all

``````
3

``````
CMIW...

emotional blind
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Posts: 383
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jan_holmes wrote:Try this input :

Code: Select all

``````
1

``````
I think the output should be :

Code: Select all

``````
3

``````
CMIW...
Oput should be

Code: Select all

``13``

FAQ
Learning poster
Posts: 84
Joined: Wed Jan 28, 2004 6:23 pm

### I still got WA

Here is my trying input

Code: Select all

``````12

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
abcdefghijklmnopqrstuvwxyz
abcdefhh
abcabcabc
0101010101
a
abefgba
``````
Line with nothing is empty string

Code: Select all

``````3
5
0
13
0
255
1
2
5
9
1
5
``````

MAK
New poster
Posts: 28
Joined: Sun Oct 23, 2005 3:44 pm

### Take the entire line as input

Yes, instead of taking a string (cin>>line in C++), take the entire line as input (use cin.getline). That way, even if the line is empty, it is still considered as valid input.

emotional blind
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Correct output

Giorgi
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Location: Georgia Tbilisi
there is no critical input. what algorithm did you use?

artie
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Joined: Sun Dec 31, 2006 11:56 am
Location: Russia
Giorgi wrote:there is no critical input. what algorithm did you use?
Hi. I am newcomer in c++ language. I got ac in the contest with pascal, but same algorithm in c++ got wa. I wish somebody explain me, what is wrong in c++ code:

Code: Select all

``````got AC
``````
Last edited by artie on Mon Jan 01, 2007 5:23 am, edited 1 time in total.

helloneo
Guru
Posts: 516
Joined: Mon Jul 04, 2005 6:30 am
Location: Seoul, Korea
artie wrote:Hi. I am newcomer in c++ language. I got ac in the contest with pascal, but same algorithm in c++ got wa. I wish somebody explain me, what is wrong in c++ code:
Taking input is faulty..
I don't know exactly what it is.. but try this..

Code: Select all

``````scanf("%d", &t);
gets(s);
while (t--) {
gets(s);
...
...
}``````

artie
New poster
Posts: 8
Joined: Sun Dec 31, 2006 11:56 am
Location: Russia
helloneo wrote:
artie wrote:Hi. I am newcomer in c++ language. I got ac in the contest with pascal, but same algorithm in c++ got wa. I wish somebody explain me, what is wrong in c++ code:
Taking input is faulty..
I don't know exactly what it is.. but try this..

Code: Select all

``````scanf("%d", &t);
gets(s);
while (t--) {
gets(s);
...
...
}``````
Thanks a lot!
Could anyone explain me why my input was faulty?

temper_3243
Experienced poster
Posts: 105
Joined: Wed May 25, 2005 7:23 am
It is a known problem. You cannot mix scanf and gets . Use scanf or gets but not both in the same program.

What happens is scanf("%d",&t) reads an integer and then stops. So the buffer has \n . now when gets reads it gets an empty line. Also don't use gets use fgets . Don't mix fgets and scanf . Use fgets and then use strtoul for integer conversion

http://c-faq.com/stdio/scanfinterlace.html

Karim
New poster
Posts: 7
Joined: Sun Sep 24, 2006 4:11 pm
Can u Explain your algorithm ..???

Thanks

emotional blind
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