1597: [Usaco2008 Mar]土地购买 Time Limit: 10 Sec  Memory Limit: 162 MBSubmit: 4026  Solved: 1473[Submit][Status][Discuss] Description 农夫John准备扩大他的农场,他正在考虑N (1 <= N <= 50,000) 块长方形的土地. 每块土地的长宽满足(1 <= 宽 <= 1,000,000; 1 <= 长 <= 1,000,000). 每块土地…

4518: [Sdoi2016]征途 题意:\(n\le 3000\)个数分成m组,一组的和为一个数,求最小方差\(*m^2\) DP方程随便写\(f[i][j]=min\{f[k][j-1]+(s[i]-s[k])^2 \}\) 发现可以斜率优化,很久没写忘记了60分暴力走人 拆开平方,\(f[i][p]=-2s_i s_k + f[k][p-1] + s_k^2 - s_i^2\) 对于两个转移\(j,k\),j比k优时\[ slope(j,k)=\frac{f[j]+s_j^2-f[k]-…

我的第二道斜率DP. 收获: 1.假设两个位置:p<q<i,然后让某一位置优,看其满足什么性质,所谓斜率优化就是满足: (g[q]-g[p])/(f[q]-f[p])  op h[i] 要化简成这样,必须满足f函数关于位置单调,否则op(<或>)的方向就会因为f的大小关系而变化,就没有凸的性质了. 2.斜率优化很难调试,所以当发现暴力DP和同样的方程被斜率优化了一下的答案不同时,不要去调试,直接去检查上面的各个函数是否写错或抄到代码中抄错了, 或者重推一遍.(注意决策点是否可能会重…

题面: 传送门 思路: 依然是一道很明显的区间dp 我们设$dp\left[i\right]\left[j\right]$表示前$j$个节点分成了$i$块的最小花费,$w\left[i\right]\left[j\right]$表示把闭区间$\left[i,j\right]$放在一起产生的价值 那么转移就比较明显了: $dp\left[i\right]\left[j\right]=min\left(dp\left[i-1\right]\left[k-1\right]+w\left[k\right…

题目链接:https://vjudge.net/problem/HDU-2829 Lawrence Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 4678    Accepted Submission(s): 2150 Problem Description T. E. Lawrence was a controversial figu…

题目链接:https://vjudge.net/problem/HDU-3480 Division Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 999999/400000 K (Java/Others)Total Submission(s): 5304    Accepted Submission(s): 2093 Problem Description Little D is really interested in the…

题目链接:https://vjudge.net/problem/HDU-3045 Picnic Cows Time Limit: 8000/4000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 3491    Accepted Submission(s): 1124 Problem Description It’s summer vocation now. After tedi…

题目链接:https://vjudge.net/problem/HDU-1300 Pearls Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 2920    Accepted Submission(s): 1464 Problem Description In Pearlania everybody is fond of pearls.…

题目链接:https://vjudge.net/problem/HDU-3507 Print Article Time Limit: 9000/3000 MS (Java/Others)    Memory Limit: 131072/65536 K (Java/Others)Total Submission(s): 14899    Accepted Submission(s): 4648 Problem Description Zero has an old printer that doe…

1911: [Apio2010]特别行动队 Time Limit: 4 Sec  Memory Limit: 64 MBSubmit: 4142  Solved: 1964[Submit][Status][Discuss] Description Input Output Sample Input 4 -1 10 -20 2 2 3 4 Sample Output 9 HINT f[i]=max{f[j]+...} 随便一化就好了 (a*(s[k]*s[k]-s[j]*s[j])+f[k]-f[…