1. Intro to USACO Strategy

2. USACO Basics If "prog" is the name of the problem:
Read from "prog.in" and write to "prog.out"
Use freopen if you use C/C++
Use BufferedReader if you use Java
Make sure class and source names match
E.g. "Main.java" and "public class Main {"
Templates:
C++:
has some useful macros
Java:
has some simplifications for i/o
Yes, putting 30 #include statements and "throws Exception" everywhere is bad style :P

3. Preparing for the USACO
train.usaco.org
Organized in chapters and sections
Has explanations for necessary algorithms
The problems get hard quickly. You do not need to know all six chapters
past USACO problems
Google them!
Miscellaneous online websites
codeforces.com
Highly recommended
Want to make gold? Try doing 300 problems :D
poj.org
Our PotWs
Free lectures, yo
Cows <3

4. USACO Tips Read the problem CAREFULLY Running time is VERY important
Check boundaries
Running time is VERY important
~108 operations per sec (conservative estimate)
Do not start coding until you know how to solve the problem
Of course, if you have no idea or are running out of time, brute force
Code!
Use Google wisely
Test your program if you have time
Check small cases by hand
Make a random test case generator

5. Random Coding Tips Watch out for off-by-one errors
Make arrays slightly bigger than needed
Watch out for overflow
int = ~109 maximum
long = ~1018 maximum
Debugging
Avoid it.
Use print statements
"Rubber duck debugging"
Variable names
l is the worst variable name ever
Use pseudocode/scratch paper
Use shortcuts
Speak to the duck

6. Things to Avoid Spending too much time on one problem
You can always come back
You need near perfect to be promoted to higher divisions
Coding a solution only to discover your method doesn't work on the sample case
Premature optimization
Being sketchy
Using long variable names
Typing takes longer than you think
Excessive commenting
Just a few words for yourself
Multitasking on your computer :'(
Avoid this.

7. What happens after my timer is over?
Congrats on your hard work
Results announced the following week
~Thursday
Rankings can be checked on tjhsst's website
~Following weekend...?
Go practice more

8. PotW! Bessie is going trick or treating. Input Format Output Format
There are N consecutive houses, numbered N.
The i_th house gives a_i pieces of candy.
Bessie must visit a nonempty consecutive sequence of houses.
Find the maximum amount of candy she can get.
Input Format
Line 1: A single integer: N
Line 2: N space separated integers: a_1 ... a_N
Output Format
Line 1: The maximum amount of candy she can get.
Constraints
15 Points: N < 1000, |a_i| < 1000
25 Points: N < 100,000, |a_i| < 10^9
35 Points: Maximize the amount of candy mod M.
Line 1: Two space separated integers, N, M
N < 100,000, 0 < a_i < M < 10^9

9. Hint for PotW Bessie is going trick or treating. Example
There are N consecutive houses, numbered N.
The i_th house gives a_i pieces of candy.
Bessie must visit a nonempty consecutive sequence of houses.
Find the maximum amount of candy she can get.
Example
N = 6, a = {1, -2, 3, -1, 4, -3}
The best sum is 3 + (-1) + 4 = 6
Notice that this is a difference of prefix-sums
( ) - (1 + -2) = 5 - (-1) = 6
How do you maximize this?
X - Y is maximized when Y is minimized.
Keep track of what sum to subtract -- you always want to subtract the most negative one.