How are this type of cheaters caught?

#	User	Rating
1	tourist	3985
2	jiangly	3814
3	jqdai0815	3682
4	Benq	3529
5	orzdevinwang	3526
6	ksun48	3517
7	Radewoosh	3410
8	hos.lyric	3399
9	ecnerwala	3392
9	Um_nik	3392

#	User	Contrib.
1	cry	169
2	maomao90	162
2	Um_nik	162
4	atcoder_official	161
5	djm03178	158
6	-is-this-fft-	157
7	adamant	155
8	awoo	154
8	Dominater069	154
10	luogu_official	150

If I am a cheater and have solutions to some problems, and for each solution, I read the code, understand it, and then write my own code from scratch based on the idea of the code I copied as if I came up with the idea myself, how can Codeforces catch me? How can the Codeforces system detect this type of cheating?

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