Does Anybody have a working COOL (Classroom Object-Oriented Language) Compiler project ??

How to solve the problem from latest Codechef Long Contest :

https://www.codechef.com/FEB16/problems/SEAPERMS

How to solve this problem from recent Codechef Long Challenge??

https://www.codechef.com/DEC15/problems/MGCHPERM/

http://usaco.org/index.php?page=viewproblem2&cpid=532 can someone elaborate the solution to this problem given at the website ?

http://www.codechef.com/COOK56/problems/STRAB/

Can someone explain the dp approach except the one given in the editorial ? Also if someone know similar problems , please provide the link :) .

To find shortest path in a directed graph with edges having weight either 0 or 1 , we often use a modification of bfs with deque. But i don't know why we push at head of the queue whenever we encounter a 0-weight edge ?