CF933A A Twisty Movement

A dragon symbolizes wisdom, power and wealth. On Lunar New Year's Day, people model a dragon with bamboo strips and clothes, raise them with rods, and hold the rods high and low to resemble a flying dragon. A performer holding the rod low is represented by a $ 1 $ , while one holding it high is represented by a $ 2 $ . Thus, the line of performers can be represented by a sequence $ a_{1},a_{2},...,a_{n} $ . Little Tommy is among them. He would like to choose an interval $ [l,r] $ ( $ 1

N/A

N/A

In the first example, after reversing $ [2,3] $ , the array will become $ [1,1,2,2] $ , where the length of the longest non-decreasing subsequence is $ 4 $ . In the second example, after reversing $ [3,7] $ , the array will become $ [1,1,1,1,2,2,2,2,2,1] $ , where the length of the longest non-decreasing subsequence is $ 9 $ .