01-复杂度2 Maximum Subsequence Sum（25 分）

Given a sequence of K integers { N​1​​ , N​2, …, NK​​ }. A continuous subsequence is defined to be { Ni, Ni+1, …, Nj} where 1≤i≤j≤K. The Maximum Subsequence is the continuous subsequence which has the largest sum of its elements. For example, given sequence { -2, 11, -4, 13, -5, -2 }, its maximum subsequence is { 11, -4, 13 } with the largest sum being 20.Given a sequence of K integers { N​1​​ , N​