P2865 [USACO06NOV]路障Roadblocks 题目描述 Bessie has moved to a small farm and sometimes enjoys returning to visit one of her best friends. She does not want to get to her old home too quickly, because she likes the scenery along the way. She has decided t…

给一手链接 https://www.luogu.com.cn/problem/P2865 这道题其实就是在维护最短路的时候维护一下次短路就okay了 #include<cstdio> #include<cstring> #include<algorithm> #include<cmath> #include<queue> using namespace std; ,inf=1e9; int read(){ ,f=,c=getchar(); ; c…

http://poj.org/problem?id=3255 Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 15680   Accepted: 5510 Description Bessie has moved to a small farm and sometimes enjoys returning to visit one of her best friends. She does not want to get…

P2865 [USACO06NOV]路障Roadblocks 题目描述 Bessie has moved to a small farm and sometimes enjoys returning to visit one of her best friends. She does not want to get to her old home too quickly, because she likes the scenery along the way. She has decided t…

·求1到n的严格次短路. [题解] dijktra魔改?允许多次入队,改了次短路的值也要入队. #include<cstdio> #include<algorithm> #define M 200010 #define N 5010 #define rg register using namespace std; int n,m,tot,last[N],dis[N],d2[N],pos[N]; struct edge{ int to,pre,dis; }e[M]; struct h…

P2865 [USACO06NOV]路障Roadblocks 最短路(次短路) 直接在dijkstra中维护2个数组:d1(最短路),d2(次短路),然后跑一遍就行了. attention:数据有不同权值的重边(40ptsQAQ) #include<iostream> #include<cstdio> #include<cstring> #include<queue> #include<cctype> using namespace std; t…

一个次短路的问题,可以套用dijkstra求最短路的方法,用dis[0][i]表示最短路:dis[1][i]表示次短路,优先队列中存有最短路和次短路,然后每次找到一条道路对他进行判断,更新最短或次短路, 注意求次短路时不要打标记,因为有可能再次访问到该节点. 最后的答案就是dis[1][n]. 1 #include<bits/stdc++.h> 2 using namespace std; 3 #define N 200010 4 int tot,head[N],to[N],w[N],nxt[…

洛谷P1879 [USACO06NOV]玉米田Corn Fields \(f[i][j]\) 表示前 \(i\) 行且第 \(i\) 行状态为 \(j\) 的方案总数.\(j\) 的大小为 \(0 \to (1 >> n - 1)\) . 第 \(i\) 行,种植状态为 \(j\) 的方案总数等于所有合法的 \(f[i-1][k]\) 之和. 状态 \(j\) 满足同一行内没有相邻的两块草地(没有共同边). 状态 \(j\) 和 \(k\) 满足相邻两行的种植情况没有两块草地有共同边. \[…

洛谷 P6218 [USACO06NOV] Round Numbers S 题目描述 如果一个正整数的二进制表示中,\(0\) 的数目不小于 \(1\) 的数目,那么它就被称为「圆数」. 例如,\(9\) 的二进制表示为 \(10011001\),其中有 \(2\) 个 \(0\) 与 \(2\) 个 \(1\).因此,\(9\) 是一个「圆数」. 请你计算,区间 \([l,r]\) 中有多少个「圆数」. 输入格式 一行,两个整数 \(l,r\). 输出格式 一行,一个整数,表示区间 \([l,…

P2866 [USACO06NOV]糟糕的一天Bad Hair Day 75通过 153提交 题目提供者洛谷OnlineJudge 标签USACO2006云端 难度普及/提高- 时空限制1s / 128MB 提交  讨论  题解 最新讨论更多讨论 题目标题 题目描述 Some of Farmer John's N cows (1 ≤ N ≤ 80,000) are having a bad hair day! Since each cow is self-conscious about her…