Code & Algorithm Jottings

Memset

• memset ( a , 0 , sizeof (a) ): Set array a to $0$

• memset ( a , -1 , sizeof (a) ): Set array a to $-1$

• memset ( a , 0x3f , sizeof (a) ): Set array a to $∞$

Define & Typedef

• If it's not nessecery, DO NOT USE DEFINE, because it will make some problem that you can't think for.

• MUST NOT use define to write the function like min ( a , b ), because if you use it like min ( a (x) , b (x) ), if a (x) is smaller than b (x), a (x) will be calculate for two times, it's much slow than the STL.

• If you want to write the type long long in another way, don't use #define int long long, use this:

typedef long long ll

Online / Unline Algorithm

• Online algorithm: Give the answer after every query.

• Unline algorithm: Give the answer while all query is asked.

Orders

• DFS Order

• In-Stack Order: The order that recursion a tree.

• Out-Stack Order: As same as in-stack-order.

Explanations

• DP: Dynamic Programming

• LCA: Least Common Ancestors

• RMQ: Range Minimum / Maximum Query