Merge k sorted arrays using heap

#1

am getting one wrong answer on submission
please tell me what test case i am not able to handle in my code

my code:
https://ide.codingblocks.com/s/51955

question link:
https://hack.codingblocks.com/contests/c/511/886

#2

your code complexity: nk log(nk)
Required complexity : n*k log(k)
Suggestion : pls use priority_queue STL.