对于长度为 的序列 , 将其分为几段, 对于段 的花费为 , 求最小花费
Zero has an old printer that doesn't work well sometimes. As it is antique, he still like to use it to print articles. But it is too old to work for a long time and it will certainly wear and tear, so Zero use a cost to evaluate this degree. One day Zero want to print an article which has N words, and each word i has a cost Ci to be printed. Also, Zero know that print k words in one line will cost
M is a const number. Now Zero want to know the minimum cost in order to arrange the article perfectly.
There are many test cases. For each test case, There are two numbers N and M in the first line (0 ≤ n ≤ 500000, 0 ≤ M ≤ 1000). Then, there are N numbers in the next 2 to N + 1 lines. Input are terminated by EOF.
A single number, meaning the mininum cost to print the article.
2010 ACM-ICPC Multi-University Training Contest（7）——Host by HIT
表示 的最小花费, 表示前缀和, 那么有
直接算就是 的, 考虑进行优化
对于 考虑当在 处转移比 处更优时, 即
于是, 我们令 , 上式就变成了