I am learning this topic of graph ,and i tried to solve basic problem of this to test my understanding.

i saw vedio from algorithms live and gone through cp algorithm blog.then i tried to solve problem in hacker earth this question and i got wa i tried till 2 hours to degub then left it this is my code.

then i tried another question on jans'light oj this problem but here also i got runtime errorthis is my code .

then i tried to solve a problem on spoj this question and again got wa my solution .

i am very demotivated now ,can some one find bug in any of my 3 plz ,plz help thanks in advance.

ps:i am not getting basic level question of cut point and bridges on code forces if you know plz share i would be very thank full.