Codeforces 1375 E. Inversion SwapSort（逆序對）

Madeline has an array 𝑎 of 𝑛 integers. A pair (𝑢,𝑣) of integers forms an inversion in 𝑎 if:ios 1≤𝑢<𝑣≤𝑛. 𝑎𝑢>𝑎𝑣. Madeline recently found a magical paper, which allows her to write two indice

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