[Explanations] Matrix (DP)
Good God DP ah
Set \ (dp (i, j) \) before said it was considering a \ (i \) column, the remaining \ (j \) a need to fill the right side of the interval is not filled , the program number
You may ask where to limit the range of the left, it can be reflected in \ (DP \) on the transfer!
Suppose not considered to limit the right section, a left section of \ (I \) long section is filled program number \ (I-len_i. 1 + \) , then the front will be less because the shorter fill a number of positions available
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