so i found this person was cheating in a lot of codeforces contest, not only once. His handle is djsksbrbf

PROOF OF CHEATING

First suspicious things was, this person is averaging solve C on Atcoder ABC which is weird for someone whose rated 1800 in codeforces and he never scored expert performance in Atcoder. Second suspicious things was some of his code are very similar to some code that has been leaked on youtube. Here's some of the proof:

First Proof:

https://mirror.codeforces.com/contest/2075/submission/311132774

https://www.youtube.com/channel/UCkDyE8XB-J7QWxnE5zkj_cQ/community?lb=UgkxnUwNaWfdVyQ-Arj-hXWusQ8sohpYL4y4

Second Proof

https://mirror.codeforces.com/contest/2071/submission/308351112

https://www.youtube.com/channel/UCkDyE8XB-J7QWxnE5zkj_cQ/community?lb=UgkxWShWDrci41FthRpLXtVSMwKiuFK_1J6M

Why would u check dist[st] == -1 if the graph was a tree lmao.

Third Proof

https://mirror.codeforces.com/contest/2071/submission/308382209

https://www.youtube.com/channel/UCkDyE8XB-J7QWxnE5zkj_cQ/community?lb=UgkxfRnxkJhUUZW7bAsCEl7Dv4G4vnTujOpl

All of them was from chunkcode01 who has been leaked his code in a lot of codeforces contest

I have another proof also, if you want another proof, just hit me up on dm, i would love to share it