As we know, USACO is a competitive programming contest primarily for secondary school students in the US. It offers a large collection of excellent problems, from the easy to the difficult. Many of the problems are educational and worthwhile as training material.

However, the official website only offers problems from as early as 2011, and older problems are hard to find. Some of the Online Judges, such as POJ, contain some of the problems, but they are not properly filed together, and it's difficult to find the corresponding solution and test data.

In this post, I will try to list all the USACO materials that I have found so far. Most of the materials come from some old websites, and thanks to the efforts of web.archive.org, we can check out old websites that no longer exist. In addition, many of the problems were used as training materials in the training of Chinese IOI teams about 20 years ago. These materials have been preserved and are available through some Chinese websites.

It is important to note that since some of the materials are from a single source, I cannot confirm that the content is the original one. Also this list is not complete, there are still a lot materials I could not find. If anyone has these materials and would like to share it, please leave it in the comments section.

USACO 2021~2022

USACO 2020~2021

USACO 2019~2020

USACO 2018~2019

USACO 2017~2018

USACO 2016~2017

USACO 2015~2016

USACO 2014~2015

USACO 2013~2014

USACO 2012~2013

USACO 2011~2012

USACO 2010~2011

USACO 2009~2010

USACO 2008~2009

USACO 2007~2008

USACO 2006~2007

USACO 2005~2006

USACO 2004~2005

USACO 2003~2004

USACO 2002~2003

USACO 2001~2002

USACO 2000~2001

USACO 1999~2000

USACO 1998~1999

USACO 1997~1998

USACO 1996~1997

USACO 1992~1996