I usually write a testcase generator for the problems I solve - I droned on about the process here. It was then a simple matter to check the output from your program against known-correct answers to random testcases until one failed 
Edit:
To be clear - I don’t know if Codechef run that particular abba testcase, but it’s definitely a testcase that exposes a flaw in your program
Okay thank you my friend for helping me out and teaching me new stuff. I have successfully removed that flaw from my code and tried to resubmit but still my submission gets rejected and its very frustrating. Here is the link of my new submission CodeChef: Practical coding for everyone
Please have a look in it.
This fails on
1
abbbabbab
I suggest re-reading the Problem very carefully, as your current approach isn’t going to work 
Okay thank you for helping me !! 
thanks once again ssjgz can u tell me how to generate testcases
Here’s lapindrome complete with testcase generator:
// Simon St James (ssjgz) - 2019-10-29
//
// Solution to: https://www.codechef.com/problems/LAPIN
//
#include <iostream>
#include <array>
#include <cassert>
#include <sys/time.h> // TODO - this is only for random testcase generation. Remove it when you don't need new random testcases!
using namespace std;
template <typename T>
T read()
{
T toRead;
cin >> toRead;
assert(cin);
return toRead;
}
constexpr auto numLetters = 26;
array<int, numLetters> letterHistogram(const string& s)
{
array<int, numLetters> letterHistogram = {};
for (const auto letter : s)
{
letterHistogram[letter - 'a']++;
}
return letterHistogram;
}
bool isLapindrome(const string& s)
{
const int length = s.length();
const auto leftHalf = s.substr(0, length / 2);
const auto rightHalf = s.substr(length - length / 2);
return letterHistogram(leftHalf) == letterHistogram(rightHalf);
}
#if 0
SolutionType solveOptimised()
{
SolutionType result;
return result;
}
#endif
int main(int argc, char* argv[])
{
ios::sync_with_stdio(false);
if (argc == 2 && string(argv[1]) == "--test")
{
struct timeval time;
gettimeofday(&time,NULL);
srand((time.tv_sec * 1000) + (time.tv_usec / 1000));
//const int T = rand() % 100 + 1;
const int T = 1;
cout << T << endl;
for (int t = 0; t < T; t++)
{
const int len = 1 + rand() % 12;
const int maxChar = 1 + rand() % numLetters;
string s;
for (int i = 0; i < len; i++)
{
s.push_back('a' + rand() % maxChar);
}
cout << s << endl;
}
return 0;
}
const auto T = read<int>();
for (int t = 0; t < T; t++)
{
const auto s = read<string>();
cout << (isLapindrome(s) ? "YES" : "NO") << endl;
}
assert(cin);
}
To generate a testcase, just run the executable and pass it the --test flag on the command-line e.g if the executable is called a.out:
./a.out --test
See also:
The implementation of the logic as given in Editorial in Python3
t = int(input())
while(t>0):
d = {'a': 0, 'b': 0, 'c': 0, 'd': 0, 'e': 0, 'f': 0, 'g': 0, 'h': 0, 'i': 0, 'j': 0, 'k': 0, 'l': 0, 'm': 0, 'n': 0, 'o': 0, 'p': 0, 'q': 0, 'r': 0, 's': 0, 't': 0, 'u': 0, 'v': 0, 'w': 0, 'x': 0, 'y': 0, 'z': 0}
s = input()
ln = len(s)
fg = 0
s1 = ""
s2 = ""
if(ln % 2 == 0):
s1 = s[:ln//2]
s2 = s[ln//2:]
# print(s1, s2)
else:
s1 = s[:ln//2]
s2 = s[(ln//2)+1:]
# print(s1, s2)
for i in s1:
d[i] += 1
for j in s2:
d[j] -= 1
# print(d)
for i in d.values():
if(i != 0):
fg = 1
break
if(fg == 1):
print("NO")
else:
print("YES")
t -= 1Consider the testcase:
5
bbcccbe
gedce
eccbdde
bdfbdbe
egafded
tnx bro…i got it…i didn’t clear the map.
Even better would be to just write your code so that this kind of problem simply can’t happen in the first place; none of l,l1,i,s or m are used outside of the while block, so why declare them there?
#include <iostream>
#include<bits/stdc++.h>
using namespace std;
int main() {
int t;
cin>>t;
while(t--)
{
int l,l1,i;
string s;
map<char,int> m;
cin>>s;
l=s.size()/2;
if(l==0)
{
cout<<"NO\n";
continue;
}
if(s.size()%2==0)
{
l1=l;
}
else
{
l1=l+1;
}
i=l1;
while(i<s.size())
{
if(m.find(s[i])==m.end())
{
m.insert(pair<char,int>(s[i],1));
}
else
m[s[i]]++;
i++;
}
for(i=0;i<l;i++)
{
if(m.find(s[i])==m.end()|| m[s[i]]==0)
{
cout<<"NO\n";
break;
}
else
m[s[i]]--;
}
if(i==l)
{
cout<<"YES\n";
}
}
return 0;
}
or better still:
#include <iostream>
#include<bits/stdc++.h>
using namespace std;
int main() {
int t;
cin>>t;
while(t--)
{
string s;
cin>>s;
const int l=s.size()/2;
if(l==0)
{
cout<<"NO\n";
continue;
}
int l1 = l;
if(s.size()%2!=0)
{
l1=l + 1;
}
int i=l1;
map<char,int> m;
while(i<s.size())
{
if(m.find(s[i])==m.end())
{
m.insert(pair<char,int>(s[i],1));
}
else
m[s[i]]++;
i++;
}
for(i=0;i<l;i++)
{
if(m.find(s[i])==m.end()|| m[s[i]]==0)
{
cout<<"NO\n";
break;
}
else
m[s[i]]--;
}
if(i==l)
{
cout<<"YES\n";
}
}
return 0;
}
but there may be repeated memory allocation and memory release for them… will it affect performance of code?
The construction of an empty string or an empty map should not involve memory allocations.
got it …Thank you sir…
whats wrong in this solution
using namespace std;
int main()
{
int i,j,count=0;
int t;
cin>>t;
while(t–)
{ int n;
string s;
cin>>s;
n=s.length();
if(n%2==0)
{
for(i=0;i<n/2;i++)
{
for(j=n/2;j<n;j++)
{
if(s[i]==s[j])
{
count++;
}
}
}
if(count==n/2)
cout<<"yes"<<endl;
else
cout<<"no"<<endl;
}
else if(n%2!=0)
{
for(i=0;i<n/2;i++)
{
for(j=(n+1)/2;j<n;j++)
{
if(s[i]==s[j])
{
count++;
}
}
}
if(count==n/2)
cout<<"yes"<<endl;
else
cout<<"no"<<endl;
}
}
return 0;
}Please either format your code or (better!) link to your submission - the forum software has mangled it and it won’t compile!
There must be some issue with the test cases.
I think there is a non-lowercase english alphabet somewhere (the question specifies only lowercase english alphabets are in the input)
I don’t see any other reason why my solution wouldn’t work : CodeChef: Practical coding for everyone
If someone finds an issue. Please let me know, thanks
https://www.codechef.com/viewsolution/35751966
May I know why the output don’t match
Repllies will be appreciated #CodeChef-DSA-learners #editorial #help #lapindrome
https://www.codechef.com/viewsolution/36790347
I Could’t understand that what’s the error in this code.
If I Put Mannual Input in this code. Its Execute sucessfully and shows the correct output. but when i submitted , this is showing wrong answer.
What should i do?