thanks. I always used the method
./a.out < input > output
and used diff command to check. I assumed online compilers also did that
someone has done it in o(k) complaxity by just sorting all given k values according to starting range value.
https://www.codechef.com/viewsolution/7956165.
can anyone explain that how this solution in correct mathematically?
Interesting! I just sorted the queries by start index (breaking ties by end index) and for each constraint I just alternated “(” and “)” from segm.begin to segm.end, overwriting any previous changes. Complexity is O(N * K), although I’m sure it can become O(N + K*log(N)) with some sort of segment trees.
Funny story. It got AC. Not sure why.
Here is my solution: link
@s1d_3: Your solution gives wrong answer for the following test case:
1
8 3
0 5
1 2
4 7
Your solution gives : (()(()() which is wrong. One correct answer could be :
(())()()
Your solution gives wrong answer for the following test case:
1
8 2
3 4
0 7
Your solution gives : ()()()() which is wrong. One correct answer could be : ()(())()
I think the test case is invalid. No correct arrangement can be made satisfying the test case. Would be surprised if you come up with a correct answer for the test case. 
Hi guys, I agree test cases for this problem were week. 
and I apologize for the same. I missed one case which lead to pass incorrect solutions, but it would not be fair to re-judge the problem. So, I will add that test case in the practice section, where you can check you solution.
while(t--)
{
char a[2001];
int n,k,x,y;
cin>>n>>k;
a[n] = '\0';
for(int i=0;i<k;i++)
{
cin>>x>>y;
a[x] = '(';
a[y] = ')';
bool isSet = 0;
for(int j = x+1;j<y;j++,isSet = !isSet)
{
if(!isSet)
a[j] = '(';
else
a[j] = ')';
}
}
cout<<a<<endl;
}
Why my solution fails can anyone give testcase on where it fails ??
That is an O(klogk + n*k) solution.
Input
1
10 4
3 6
2 9
4 5
8 9
Output should be ((((()))()
but those codes like https://www.codechef.com/viewsolution/7962854 and many others
giving output as ((()()()() are also accepted, which is wrong. So please rejudge
Your code outputs “(())” for that test case!
What is the problem with this code? Only the first substask is passing.
Please can u provide the test cases.
#include
#include
using namespace std;
int main()
{
long long int t,n,k,i,x,y;
cin>>t;
while(t–)
{
cin>>n>>k;
char arr[n];
for(i=0;i<n-1;i+=2)
{
arr[i]=’(’;
arr[i+1]=’)’;
}
// cout<<endl;
// cin>>x>>y;
// arr[x]=’(’;
// arr[y]=’)’;
// low=x;
// high=y;
//k=k-1;
while(k–)
{
cin>>x>>y;
for(i=x;i<y;i+=2)
{
//if(arr[i]==’(’)
// break;
//else
{
arr[i]=’(’;
arr[i+1]=’)’;
}
}
//arr[x]='(';
//arr[y]=')';
//if(x<low)
// low=x;
// if(y>high)
//high=y;
}
/* c=0;
//cout<<high<<" "<<low<<endl;
mid=((high-low)+1)/2;
//cout<<mid<<endl;
for(i=0;i<low;i++)
arr[i]='(';
for(i=low;i<=high;i++)
{
if(arr[i]=='0' && c < mid)
{
arr[i]='(';
c++;
}
else if(arr[i]=='(')
c++;
else if(arr[i]==')')
c--;
else
{ arr[i]=')';
c--;
}
}
for(i=high+1;i<n;i++)
arr[i]=')';
//cout<<arr<<endl;*/
for(i=0;i<n;i++)
cout<<arr[i];
cout<<endl;
}
return 0;
}
I have never got so may wrong answers for a question as in this one.Still unable to find a test case where this fails.Please someone find a test case for me…I have matched with all the test cases of this page and all those cases works fine in my code…Link to my code:
https://www.codechef.com/viewsolution/7951755
In the column “Breaking down the partially intersecting constraints into simpler form:”
what if length of the segment [c,b] is odd?
Y this code fails ??
while(t--)
{
char a[2001];
int n,k,x,y;
cin>>n>>k;
a[n] = '\0';
for(int i=0;i<k;i++)
{
cin>>x>>y;
for(int j = x;j<=y;j+=2)
{
a[j] = '(';
a[j+1] = ')';
}
}
cout<<a<<endl;
}
I have to re-post it, but still the question in practice is still accepting the incorrect solutions and it gave wrong answer to my correct solution, that’s totally disappointing from the codechef…
Codechef should also not include this contest for calculating the rating coz it has an erroneous problem which gave many users including me WA during the contest and the actual in-correct solution were passed giving them AC… one way for codechef to improve and make up for their error…
here is test case like
1
8 1
0 1
it contain only () and other character are only null character …how the you can print n character string in output…I think that’s It gave WA?..