In your query function , you are always merging the two children nodes data. This is wrong , because one child's interval doesn't necessarily intersect with the query interval. So , changing your query function to the following yields ACCEPTED. Congratulations :-)

segment query(int n, int b, int e, int x, int y)
{
    if(b > e || b > y || e < x) return segment(MIN_VALUE, MIN_VALUE, MIN_VALUE, MIN_VALUE);
    else if(x <= b && e <= y) return tree[n]; 
    segment A = query(2*n, b, (b+e)/2, x, y);
    segment B = query(2*n+1, (b+e)/2+1, e, x, y);
    if(A.tMax == MIN_VALUE) /* Is A completely irrelevant ? Ignore it ! */
 	return B;
    if(B.tMax == MIN_VALUE) /* Is B completely irrelevant ? Ignore it ! */
	return A;

     /* We know for sure that at least one of segments A , B is relevant to the query interval , otherwise we would have exited the recursion by the first line in this function */
     return merge(A , B); /* Both A and B are relevant for the query interval , Merge Them ! */
}