PROBLEM LINK:Author: Kamil Dębowski DIFFICULTY:Cakewalk PREREQUISITES:Elementary math PROBLEM:For a given infinite ladder graph $G$ with vertices numbered from $1$, and integer $Q$, the goal is to answer $Q$ queries. Each query contains two integers $a$ and $b$ and asks if there is an edge between vertices $a$ and $b$ in $G$. There are $3$ types of edges between vertices of $G$:
EXPLANATION:In order to solve the problem, we are going to answer queries one after another. For a fixed query $(a, b)$, we simply check if $a, b$ can form an edge within any of the classes defined above. Notice that performing such a check for each class is easy: Class 1: Checking if $a, b$ forms an edge of the first class can be done by just checking if the smaller label is odd and the difference between the larger and the smaller label is exactly $1$. Classes 2 and 3: Checking if $a, b$ forms an edge of either the second or the third class can be done by just checking if the difference between the larger and the smaller label is exactly $2$. Since performing each of the above checks takes a constant time, the total complexity of the solution is $O(Q)$. AUTHOR'S AND TESTER'S SOLUTIONS:
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asked 25 Mar '17, 19:03

The links of first tester's solution and second tester's solution are not working again(also not working in SPECIES). answered 26 Mar '17, 00:51

Hello everyone, I am new here. Can someone guide me what I am doing wrong in the following code. Seems to run fine when i check it on my computer but when i submit it on codechef, it says wrong answer. thank you
answered 02 Apr '17, 15:52

Hello everyone.. Another approach of solving this problem can be: 1.finding minimum of two...min(a,b) 2.finding maximum of two...max(a,b)
answered 02 Apr '17, 19:06

My code isn't working. It works fine on my computer but when I submit it to codechef...it shows that I have a wrong answer...Can someone please please please tell me what is wrong with my code. include <stdio.h>int main() { int i,queries,city_1,city_2; printf("Enter the number of queries you would like to check:\n"); scanf("%d",&queries); while(queries<=0) {
i=city_11; if (i%2==0) printf("YES\n"); } if(city_1city_2==2  city_2city_1==2) printf("YES\n"); else printf("NO\n");
return 0; } answered 12 May '17, 00:58

Please upvote me I don't have enough karma points to ask question. Thank you! answered 12 May '17, 08:14

I think it would be noteworthy to mention that one is not expected to check whether for example the road no. 3 and road no. 7 connects or not. Although it remains ambiguous in the question. I hope may be it gets mentioned in the editorial .If I am not wrong you just need to find the immediate road that is connected to the first no. "a". answered 11 Jun '17, 23:37
