题目大意:给你很多条线段,开头结尾是$[l,r]$,让你覆盖整个区间$[1,T]$,求最少的线段数 题目传送门 线段树优化$DP$裸题.. 先去掉所有能被其他线段包含的线段,这种线段一定不在最优解里 排序,让所有线段构成左右端点位置都递增的排列 定义$f[i]$表示第$i$条线段,覆盖到第$i$条线段右端点时,需要的最少的线段数 $f[i]=min(f[j]+1)\;(j<i,r[j]>=l[i])$ 朴素是$n^2$转移的 开一棵最小值线段树,记录从$1$覆盖到位置$x$的最少线段数 每次求…

题意 POJ2376 Cleaning Shifts 0x50「动态规划」例题 http://bailian.openjudge.cn/practice/2376 总时间限制: 1000ms 内存限制: 65536kB 描述 Farmer John is assigning some of his N (1 <= N <= 25,000) cows to do some cleaning chores around the barn. He always wants to have one c…

[题目链接] http://www.tsinsen.com/A1219 [题意] 给定一棵树,a[u][i]代表u结点分配i人的收益,可以随时改变a[u],查询(u,v)代表在u子树的所有节点,在u->v(不含u)路径上的节点分配人数的最优收益. [思路] 树链剖分:构造重链时先访问重儿子,因此一个重链的区间连续,同时一个子树的区间连续. 查询分为两部分:构造在u子树内分配人数i的最大收益ans1[i],以及构造在u->v路径上一个结点分配人数i的最大收益ans2[i].则ans=max{ a…

HDU 3016 Man Down (线段树+dp) Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 1391    Accepted Submission(s): 483 Problem Description The Game “Man Down 100 floors” is an famous and interesting ga…

Cleaning Shifts Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 32561   Accepted: 7972 Description Farmer John is assigning some of his N (1 <= N <= 25,000) cows to do some cleaning chores around the barn. He always wants to have one co…

[Usaco2005 Dec] Cleaning Shifts 清理牛棚 题目描述 Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer John, the most obliging of farmers, has no choice but hire some of th…

题目描述 Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer John, the most obliging of farmers, has no choice but hire some of the cows to clean the barn. Farmer John…

$Poj$    $AcWing$    $Luogu$ $ps:$洛谷题目与$Poj$略有不同,以下$Description$是$Poj$版.题目的不同之处在于洛谷中雇用奶牛的费用不相同,所以不可以用贪心法,只能$DP$ $Description$ $Sol$ 就是区间覆盖问题$qwq!$ 1.$DP$做! $F[i]$表示覆盖$[1,i]$所需要的最小牛个数 把牛的工作时间按照右端点(结束时间)r[i]从小到大排序,按顺序扫描这些牛.设当前为第$i$头牛,则: $F[r[i]]=(min_{…

题目传送门 清理牛棚 题目描述 Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer John, the most obliging of farmers, has no choice but hire some of the cows to clean the barn.…

//Accepted 7552 KB 844 ms //dp[i]=sum(dp[j])+1 j<i && a[j]<a[i] //可以用线段树求所用小于a[i]的dp[j]的和 //需要离散化 #include <cstdio> #include <cstring> #include <iostream> #include <queue> #include <cmath> #include <algorithm…