Runtime error cause

1. Brackets

I found it by accident when I was doing the question!

(For details, seeElse if (arefriends(X, Y)=-1)

4.Endless loop

I just found another one. It was so bad luck that I met.

(For details, seePoj 2236 Wireless Network)

 

If (X! = Y) // -------- there must be no less judgment here. Otherwise, an endless loop occurs and a runtime error occurs during submission.
Set [x] = y;

This question is a tree-based and query-set question,

Because the set [] array saves the parent node, if no judgment condition is added,

It is equivalent to pointing to itself. an endless loop will appear in the function of the compression path, and the end condition (that is, the root) cannot be found)