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效果如下

In the first test case, one possible optimal sequence of operations is: $[\color{red}{1}\color{black},3,3] \rightarrow [2, \color{red}{3}\color{black}, 3] \rightarrow [\color{red}{2}\color{black}, 4, 3] \rightarrow [\color{red}{3}\color{black}, 4, 3] \rightarrow [4, 4, 3]$ 。

In the second test case, one possible optimal sequence of operations is: $[1, \color{red}{3}\color{black}, 4, 5, 1] \rightarrow [1, \color{red}{4}\color{black}, 4, 5, 1] \rightarrow [1, 5, \color{red}{4}\color{black}, 5, 1] \rightarrow [1, 5, \color{red}{5}\color{black}, 5, 1] \rightarrow [1, \color{red}{5}\color{black}, 6, 5, 1] \rightarrow [1, \color{red}{6}\color{black}, 6, 5, 1] \rightarrow [1, 7, 6, 5, 1]$

LATEX如下：

In the first test case, one possible optimal sequence of operations is: $[\color{red}{1}\color{black},3,3] \rightarrow [2, \color{red}{3}\color{black}, 3] \rightarrow [\color{red}{2}\color{black}, 4, 3] \rightarrow [\color{red}{3}\color{black}, 4, 3] \rightarrow [4, 4, 3]$ 。

In the second test case, one possible optimal sequence of operations is: $[1, \color{red}{3}\color{black}, 4, 5, 1] \rightarrow [1, \color{red}{4}\color{black}, 4, 5, 1] \rightarrow [1, 5, \color{red}{4}\color{black}, 5, 1] \rightarrow [1, 5, \color{red}{5}\color{black}, 5, 1] \rightarrow [1, \color{red}{5}\color{black}, 6, 5, 1] \rightarrow [1, \color{red}{6}\color{black}, 6, 5, 1] \rightarrow [1, 7, 6, 5, 1]$