Solved by shepherd_nullptr

#	Title	# Solved	Avg. Tries
1657	두부장수 장홍준	700	2.02
2150	Strongly Connected Component	4,639	2.20
3491	Skyscraper Floors	10	10.80
3653	Movie collection	2,828	2.21
3679	Simple Polygon	989	3.92
4315	Marbles on a tree	111	2.24
5012	Mega Inversions	440	2.15
5820	경주	588	4.76
5822	악어의 지하 도시	115	2.43
6549	Largest Rectangle in a Histogram	10,667	3.66
9126	Cycling	13	5.38
9250	문자열 집합 판별	1,126	2.76
9537	Magical GCD	148	3.45
10745	Censoring	72	5.26
11280	2-SAT - 3	1,909	1.94
11438	LCA 2	7,040	3.04
11689	GCD(n, k) = 1	4,294	2.50
13007	ntopia	53	1.34
13426	단순 경로의 수열의 도치	9	1.78
14258	XOR 그룹	70	2.56
14749	Grasshopper Route	81	2.58
16044	Prefix Free Code	16	1.75
16229	반복 패턴	200	4.27
17004	Subsequences in Substrings	32	1.16
17157	Hobson’s Trains	30	2.57
18118	7-세그먼트 디스플레이	109	4.26
21148	TripTik	10	3.10
21225	Index	56	1.50
21586	Another Substring Query Problem	35	4.14
21592	Longest Common Substring	72	2.00
21882	Coins on a tree	47	3.68
22911	Hidden Pancakes	46	1.80
23078	Star Trappers	13	3.92
23195	Gene Folding	24	1.79
23196	Landscape Generator	44	1.43
24023	아기 홍윤	340	2.26
24452	交易計画 (Trade Plan)	29	1.93
24602	Tree Hopping	40	2.63
25913	전투 시뮬레이션	39	3.41
26130	Crystal Crosswind	27	1.26
26140	Take On Meme	13	1.23
26141	Where Am I?	25	1.44
27576	Eroding Pillars	5	1.80
27592	Triangle Containment	12	1.33
27889	Exceptional School Name	3,896	1.41
28088	응애(EASY)	172	1.98
28145	A Tree and Two Edges	17	2.35
29772	병사 분배	16	2.38
30880	Query Isn’t ROCK	42	4.40
30947	Cakes	17	1.41

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