I am not the setter of the problem. 
I’ll ask Ankit to reply.
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What causes NZEC in python I submitted a code in python , i tested in Codechef IDE which gave appropriate output when i submitted the same for the problem it gave me an NZEC
When i just wrote the same algo code in C++ 4.92 it gave me AC
Here is the link
Can someone help me understand why this solution http://ideone.com/4PRXeG gave me WA. It works perfectly for the example given above and for any other test cases i could think off using the same logic as described above.
Can anybody please help me with my code that why it’s giving TLE .
Here’s a brief about what i have done.
CHECK 1 : if the input string is odd sized then if k>1 print -1 , else print string.
CHECK 2 : if the input string is irregular then if k>1 print -1 else print string.
CHECK 3 : i have converted the whole string from ‘(’ and ‘)’ to characters ‘a’ and ‘b’.
Then using the string concatenation operation and with the help of two temporary strings
generated all n-1 strings and hashed them into an map.
then finally checked if k>map.size() print -1
else find kth position in map and print that string after converting it back.
since i have used map . complexity would hardly go nlogn . and for 10^5 and at most 10 test cases . it would go 2 * (10^7) which goes strictly in 1 second. so why tle .?
here’s my
[1] .
[1]: http://ideone.com/l4J6rFCan anyone tell me for which test case this solution http://www.codechef.com/viewsolution/7267574 is not working .?
Even i had same problem
Hi, I am glad you found the problem interesting.
However, the story behind this problem is not so interesting :P.
I proposed a version of this for cakewalk where you had to find only the lexicographically smallest. However, it seemed a little harder than a 1st problem should be yet, easier than 2nd problem
So, I just modified it to ask for kth subsequence and tried to solve it myself. Needless to say, I was equally amazed upon finding such a beautiful pattern 
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That’s because adding strings is not the same thing as adding integers!
In line 59, you have a string final with 0 length. Then you reach line 63, where it has length n - 1. Notice that string concatenation takes time: O(number_of_characters_added). So, you have are doing n - 1 operations inside a loop that runs atleast n times. Thus, you have quadratic complexity and get TLE.