链接
http://acm.hdu.edu.cn/showproblem.php?pid=6249
描述
给定包含1至n,n个点的点集, ( 1 ≤ n ≤ 2000 ) (1 \leq n \leq 2000 ) (1≤n≤2000)
再给定 m个区间 [ a , b ] [a,b] [a,b] ( 1 ≤ a ≤ b ≤ n ) (1 \leq a \leq b \leq n ) (1≤a≤b≤n)
求取k个区间对应的点集,使得其并集最大
分析
先拆分这m个区间,
[ a , b ] [a,b] [a,b] 拆分为
[ a , b ] , [ a + 1 , b ] , [ a + 2 , b ] , . . . , [ b − 2 , b ] , [ b − 1 , b ] , [ b , b ] [a,b],[a+1,b],[a+2,b],...,[b-2,b],[b-1,b],[b,b] [a,b],[a+1,b],[a+2,b],...,[b−