Dijkstra algorithm getting wrong answer even if code is correct

[aji13]

Here is the problem: https://www.spoj.com/problems/EZDIJKST/
Here is the submission: https://ideone.com/1QIxH2

I submit the same submission in cses online judge and it got accepted. And I am sure, constraints are not the problem, so what can be wrong ?

[simes]

vector distance(n, INT64_MAX);
if (res[n] < INT64_MAX) {

What’s wrong with these lines?