Codeforces Round #834 (Div. 3)

F. All Possible Digits

https://codeforces.com/contest/1759/problem/F

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Educational Codeforces Round 138 (Rated for Div. 2)

D. Counting Arrays

https://codeforces.com/contest/1749/problem/D

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Educational Codeforces Round 137 (Rated for Div. 2)

D. Problem with Random Tests

https://codeforces.com/contest/1743/problem/D

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Codeforces Round #828 (Div. 3)

E1. Divisible Numbers (easy version)

https://codeforces.com/contest/1744/problem/E1

E2. Divisible Numbers (hard version)

https://codeforces.com/contest/1744/problem/E2

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Codeforces Global Round 23

C. Permutation Operations

https://codeforces.com/contest/1746/problem/C

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