题目链接 参考. \(Description\) 将\(1,2,\cdots,n(n\leq 300)\)依次入栈/出栈,并满足\(m(m\leq 90000)\)个形如\(x\)要在\(y\)之前出栈的限制,问合法的出栈序列有多少种. \(Solution\) 没有限制就是个卡特兰数,但有了限制就要考虑好好DP了.. 序列的入栈&出栈顺序可以构成一棵二叉树,且每一棵子树中的点一定比该子树的根节点出栈早. \(f[i][j]\)表示子树根节点为\(i\),其中的点是\(i\sim j\),\(i…

题目:http://acm.hdu.edu.cn/showproblem.php?pid=5181 题解:https://www.cnblogs.com/Miracevin/p/10960717.html 原来卡特兰数的这个问题还能区间DP…… XO #include<cstdio> #include<cstring> #include<algorithm> #define ll long long using namespace std; int rdn() { ;;…

http://acm.hdu.edu.cn/showproblem.php?pid=5181 题意: 有一个栈,其中有n个数1~n按顺序依次进入栈顶,在某个时刻弹出. 其中m个限制,形如数字A必须在数字B之前弹出. 求方案总数   dp[i][j]表示数字i~j的出栈方案数 枚举最后一个出栈的数k,若k合法 dp[i][j]+=dp[i][k]*dp[k+1][j] 如何判断k是否合法?   对于一组i,j,k来说,它的弹出顺序是 [i,k-1]早于[k+1,j]早于k 对于一个限制 A必须在B…

HDOJ(HDU).1058 Humble Numbers (DP) 点我挑战题目 题意分析 水 代码总览 /* Title:HDOJ.1058 Author:pengwill Date:2017-2-15 */ #include <iostream> #include <cstdio> #include <algorithm> #include <cstring> #define nmax 6000 #define min(a,b) (a<b?a:b…

http://acm.hdu.edu.cn/showproblem.php?pid=3709 Problem Description A balanced number is a non-negative integer that can be balanced if a pivot is placed at some digit. More specifically, imagine each digit as a box with weight indicated by the digit.…

XHXJ's LIS Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 2265    Accepted Submission(s): 927 Problem Description #define xhxj (Xin Hang senior sister(学姐)) If you do not know xhxj, then careful…

http://acm.hdu.edu.cn/showproblem.php? pid=4123 Problem Description Bob wants to hold a race to encourage people to do sports. He has got trouble in choosing the route. There are N houses and N - 1 roads in his village. Each road connects two houses,…

http://acm.hdu.edu.cn/showproblem.php?pid=4507 Problem Description 单身! 依旧单身! 吉哥依旧单身! DS级码农吉哥依旧单身! 所以.他生平最恨情人节,无论是214还是77.他都讨厌! 吉哥观察了214和77这两个数,发现: 2+1+4=7 7+7=7*2 77=7*11 终于,他发现原来这一切归根究竟都是由于和7有关!所以,他如今甚至讨厌一切和7有关的数. 什么样的数和7有关呢? 假设一个整数符合以下3个条件之中的一个.那么我…

You Are the One Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 3348    Accepted Submission(s): 1524 Problem Description The TV shows such as You Are the One has been very popular. In order to m…

HDU 2829 区间DP & 前缀和优化 & 四边形不等式优化 n个节点n-1条线性边,炸掉M条边也就是分为m+1个区间 问你各个区间的总策略值最少的炸法 就题目本身而言,中规中矩的区间DP问题 d p[i][j]表示前i个节点,分为j个区间的最优策略值 cost[i][j]为从i到j节点的策略值 所以dp[i][j] = min(dp[k-1][j-1] + cost[k][i] 但是复杂度太高了 可以优化的地方有: cost数组值得求取: 考虑到cost(i,j)=ΣAxAy (i≤…