My code is printing different outputs when i print something additionally . If i print the line 15 (mentioned in my code) I get a different output , whereas if I do not print that line I get a different final output . Can you please help me know why ?
Here is the question link . question
My code is below . Any help will be really appreciated .
/*this is the code */
#include<bits/stdc++.h>
using namespace std;
typedef long ll ;
int main()
{
string s1,s2;
getline(cin,s1);
getline(cin,s2);
ll f1[26]={0};
ll f2[26]={0};
ll n = s1.length();
ll l2 = s2.length();
cout<<l2<<endl;
/* printing the above line chages final answer. why??? */
for(ll i = 0 ; i<l2 ; i++)
{
if(s2[i]!=' ')
f2[s2[i]-97]++;
}
ll l=-1,r=-1,ans=-1,lans=99999,count = 0;
while(l<n && r<n)
{
if(count==l2)
{
if(l<n && l>=0)
{
int len = r-l+1;
if(len<lans)
{
lans = len;
ans = l;
}
if(f2[s1[l]-97]>0)
{
f1[s1[l]-97]--;
if(f1[s1[l]-97]<f2[s1[l]-97])
count--;
}
}
l++;
}
else
{
r++;
if(r<n && r>=0)
{
if(f2[s1[r]-97]>0)
{
f1[s1[r]-97]++;
if(f1[s1[r]-97]<=f2[s1[r]-97])
count++;
}
}
}
}
string ss = s1.substr(ans , lans);
cout<<ss<<endl;
}
LINK = compiler link .
This is a link to my compiled code please refer to this .
2 Likes
Wow . I got the answer for this strange behaviour .
Instead of using
typedef long ll;
we use
typedef int ll;
and everything works just fine . This is strange to me .
Would be great if anyone could help clear this or lead to a link to clear this confusion .
If we replace endl with “\n” in line 15, output remains same as commenting that line . So basically the answer is difference between endl and “\n”, but I can’t figure out any further!
1 Like
Wow . This is even more confusing now . Well , my above comment explains that I was refering to the string index using long instead of int data type so I thought there was the error . But different output using \n and endl leads to a completely new discussion here .
1 Like
You could put this problem on stackoverflow. They might have a solution.
1 Like
Yes . But I do not have an id there . Will surely go for other platforms like stackoverflow if I do not get any help here on codechef . But I guess there would be many people on codechef facing errors like this in their daily coding . Hope they come to rescue .
1 Like
If you run this on Compile and run the code with online compiler and IDE | CodeChef, this will give the same solution in both the cases.
One reason that I am aware of is, that things like fflush are completely compiler dependent, so this strange behaviour is not reproducible.
1 Like
Sorry but codechef ide also gives 2 different answers .
And i do not think that fflush has anything to do with it because with or without them , the problem still exists .
OK . Now i have found the answer finally by careful observation .
The only thing that is causing problem here is that I am using statements like
f1[s1[r]-97];
and accessing other array indexes without checking if s1[r]-97 is non negative .
It is negative when s1[r] is a space .
So just checking this condition if (s1[r]-97>=0) and then accessing array index solves all the complexities .
Thank you to everyone for their time to help me out 
All this undefined behaviour because i was accessing array indices with negative values .
I was accessing f1[s1[r]-97] without making sure if (s1[r]-97 is >=0) .(which will be negative if s1[r] is a space character . ASCII val = 32)
Adding the above condition before accessing array index solves all the problem of using endl or “\n” or int or long .
Thanks for your time though .Really appreciate it @shivamshivi99