Solved by shepherd_nullptr

#	Title	# Solved	Avg. Tries
1657	두부장수 장홍준	748	2.03
2150	Strongly Connected Component	4,954	2.22
3491	Skyscraper Floors	10	10.80
3653	Movie collection	3,011	2.21
3679	Simple Polygon	1,106	3.87
4315	Marbles on a tree	121	2.20
5012	Mega Inversions	469	2.12
5820	경주	646	4.67
5822	악어의 지하 도시	115	2.43
6549	Largest Rectangle in a Histogram	11,479	3.61
9126	Cycling	15	5.40
9250	문자열 집합 판별	1,214	2.76
9537	Magical GCD	165	3.42
10745	Censoring	73	5.21
11280	2-SAT - 3	2,113	1.97
11438	LCA 2	7,615	3.03
11689	GCD(n, k) = 1	4,831	2.49
13007	ntopia	61	1.31
13426	단순 경로의 수열의 도치	10	1.70
14258	XOR 그룹	74	2.51
14749	Grasshopper Route	87	2.52
16044	Prefix Free Code	16	1.75
16229	반복 패턴	236	4.44
17004	Subsequences in Substrings	36	1.14
17157	Hobson’s Trains	32	2.53
18118	7-세그먼트 디스플레이	109	4.26
21148	TripTik	10	3.10
21225	Index	63	1.57
21586	Another Substring Query Problem	38	3.89
21592	Longest Common Substring	80	1.93
21882	Coins on a tree	50	3.60
22911	Hidden Pancakes	52	1.75
23078	Star Trappers	14	3.79
23195	Gene Folding	26	1.73
23196	Landscape Generator	48	1.42
24023	아기 홍윤	354	2.27
24452	交易計画 (Trade Plan)	33	1.94
24602	Tree Hopping	50	2.40
25913	전투 시뮬레이션	43	3.28
26130	Crystal Crosswind	28	1.25
26140	Take On Meme	19	1.16
26141	Where Am I?	22	1.50
27576	Eroding Pillars	7	3.00
27592	Triangle Containment	18	1.44
27889	Exceptional School Name	4,680	1.41
28088	응애(EASY)	198	1.96
28145	A Tree and Two Edges	19	2.21
29772	병사 분배	21	2.29
30880	Query Isn’t ROCK	45	4.29
30947	Cakes	27	1.81

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