B.Blow up the city
solved by F0_0H 210min
Meaning of the title number to a DAG, ask each given u, v, or v such that u can not find communication with the center of the key points
practice
- In accordance with the order topology achievements
- Added father node for the node precursor of lca
- The answer queries, simply output u, v two depth, depth minus lca
G. Find the answer
solved by rdc 50min -2
That Italy : the query interval up to a few figures and equal to less than m.
Practice : Weight segment tree.