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2021-IMOC qualification
C1
C1
Part of
2021-IMOC qualification
Problems
(1)
String with As and Bs
Source: 2021 IMOC qualification problems, C1
12/30/2021
There are
3
n
3n
3
n
A
A
A
s and
2
n
2n
2
n
B
B
B
s in a string, where
n
n
n
is a positive integer, prove that you can find a substring in this string that contains
3
3
3
A
A
A
s and
2
2
2
B
B
B
s.
IMOC
combinatorics