agc026 c

from Typical ideas for coming up with solutions in competitive programming agc026_c https://atcoder.jp/contests/agc026/tasks/agc026_c

• Thoughts.
  • How much does 18C9 cost… - Estimating computational quantities
    • I can afford 13, and 15 is too much to ask for, so 18 is a no-go.
    • Added: It was 36C18.
  • You can always assume that the number is even and the left end is red (since there is always a red-blue inverted one).
• Official Explanation
  • I see, Principle of 10 coins.
    • Since the blue letters are N and the right half is also N, we can say “the number of blue letters on the left matches the number of red letters on the right”.
  • If you halve it, you get 2^18, which is okay if you do a full search.
    • A kind of half-full enumeration?

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