Problem A. My Last ABC Problem

Only came up with violent dp. . . The key is to examine the number of different adjacent positions in the interval. .

Set to x, the answer is the ceil(x/2) of this value, which proves that the pigeonhole principle can be used.

Problem B. Arrange Your Balls

On the contrary, I think it is simpler than A, sorting from large to small, just construct dfs().

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