Split the Sticks
Spring Love
Stargazing
Strange Matrix
Strange Transformation
Codeforces Round 589 (Div. 2) D. Complete Tripartite
Codeforces Global Round 5 C2. Balanced Removals (Harder)
Educational Codeforces Round 74 (Rated for Div. 2) D. AB-string
Codeforces Round 599 (Div. 1) B. 0-1 MST
Codeforces Round 597 (Div. 2) D. Shichikuji and Power Grid