• Codeforces (also has SGU under acmsguru)

• Atcoder (also has JOI problems)

• DMOJ (IOI and ICPC problems)

• Kattis (ICPC problems)

• Advent of Code

• Timus

• Project Euler

• dunjudge.me

• UVa Online Judge/Online Judge

• Topcoder

• CodeChef

• oj.uz (IOI and ICPC)

• acmicpc.net (ICPC problems like Live Archive)

• USACO

• Leetcode

• Hackerrank

• e-olymp (olympiad)

• toph.co

• acmp.ru

• judtge.org

• URI Online Judge (ICPC)

• SPOJ

• PEG (migrated to DMOJ)

• CSES

I'm in college (sophomore), but my only reason for going to it is to be in the ICPC competition because as far as I know there's no other cp competitions near me that you can go to as easily. Right now I don't care about having a college degree because I don't think I would care what job I have and college and high school have sapped me of my energy too much to be worth it.

My parents (who have failed to convince me) and a professor I talked to say there's a value to a college degree but before I talk to them more about it I would like to know if anybody else has been in a similar situation and what they did or if you have anything to say about my plan.

I'm having trouble understanding the statement of problem D of the Nikkei contest (https://atcoder.jp/contests/nikkei2019-qual/tasks/nikkei2019_qual_d?lang=en). It says that the original tree is unique, but for the first sample case, the original tree can also be 1 -> 2 and 1 -> 3, right?