题目链接:https://www.luogu.org/problemnew/show/P2936 菜 #include <queue> #include <cstdio> #include <cstring> #include <iostream> #include <algorithm> using namespace std; const int maxn = 10000; const int inf = 1e9; int n, m, s,…

P2936 [USACO09JAN]全流Total Flow 题目描述 Farmer John always wants his cows to have enough water and thus has made a map of the N (1 <= N <= 700) water pipes on the farm that connect the well to the barn. He was surprised to find a wild mess of different…

题目描述 Farmer John always wants his cows to have enough water and thus has made a map of the N (1 <= N <= 700) water pipes on the farm that connect the well to the barn. He was surprised to find a wild mess of different size pipes connected in an appa…

题目描述 Farmer John always wants his cows to have enough water and thus has made a map of the N (1 <= N <= 700) water pipes on the farm that connect the well to the barn. He was surprised to find a wild mess of different size pipes connected in an appa…

题目描述 Farmer John always wants his cows to have enough water and thus has made a map of the N (1 <= N <= 700) water pipes on the farm that connect the well to the barn. He was surprised to find a wild mess of different size pipes connected in an appa…

题目描述 Farmer John always wants his cows to have enough water and thus has made a map of the N (1 <= N <= 700) water pipes on the farm that connect the well to the barn. He was surprised to find a wild mess of different size pipes connected in an appa…

题 裸题不多说,在网络流的练习题里,你甚至可以使用暴力. #include<bits/stdc++.h> using namespace std; typedef long long ll; typedef pair<int,int> pii; template<typename T>inline :;} template<typename T>inline :;} template<typename T>inline T _min(T A,T…

链接一下题目:luoguP3128 [USACO15DEC]最大流Max Flow(树上差分板子题) 如果没有学过树上差分,抠这里(其实很简单的,真的):树上差分总结 学了树上差分,这道题就极其显然了,不就是把每一条运输路线差分进去,那就是板子了啊. 树上差分还是很有用的,比较容易写,这种询问很少的题目去敲那么长(还容易出玄学错误)的树剖很浪费,用树上差分就很快了!(//...微笑...\\) 上一波代码: #include<iostream> #include<cstdlib>…

题目链接:https://www.luogu.org/problemnew/show/P3128 菜 #include <cstdio> #include <cstring> #include <iostream> #include <algorithm> #define ll long long #define lson left, mid, rt<<1 #define rson mid+1, right, rt<<1|1 usin…

题目描述 Farmer John has installed a new system of N-1N−1 pipes to transport milk between the NN stalls in his barn (2 \leq N \leq 50,0002≤N≤50,000), conveniently numbered 1 \ldots N1…N. Each pipe connects a pair of stalls, and all stalls are connected t…

题意:一棵树,多次给指定链上的节点加1,问最大节点权值 n个点,n-1条边很容易惯性想成一条链,幸好有样例.. 简单的树剖即可!(划去) 正常思路是树上差分,毕竟它就询问一次.. #include<iostream> #include<cstring> #include<cstdio> using namespace std; inline int rd(){ ,f=;char c; :; +c-',c=getchar(); return ret*f; } <&l…

题目链接 luogu P2934 [USACO09JAN]安全出行Safe Travel 题解 对于不在最短路树上的边(x, y) 1 | | t / \ / \ x-----y 考虑这样一种形态的图, '-' 标记为非最短路树的边 对于边集(x, t)内的任意一点 i, 到达它的所有方式一定是 1 -> t -> y -> x -> i 这样就可以对树边(x, t)标记 Min = dis[y] + dis[x] + W_{x,y} 每个点在标记中取最小 Answer_i 就是…

Farmer John always wants his cows to have enough water and thus has made a map of the N (1 <= N <= 700) water pipes on the farm that connect the well to the barn. He was surprised to find a wild mess of different size pipes connected in an apparentl…

3396: [Usaco2009 Jan]Total flow 水流 Time Limit: 1 Sec  Memory Limit: 128 MBSubmit: 45  Solved: 27[Submit][Status] Description   Input 第1行输入N,之后N行每行描述一条水管,前两个英文字母表示水管的两端(大小写字母是不一样的),后一个整数表示水管的流量,流量不会超过1000. Output 一个整数,表示总流量． Sample Input 5 A B 3 B C 3…

题目链接 bz似乎挂了... luogu P3305 [SDOI2013]费用流 题解 dalao告诉我,这题 似乎很水.... 懂了题目大意就可以随便切了 问1,最大流 问2,二分最大边权求,check是否为最大流 PS:今天代码很多bug....惨orz 代码 #include<queue> #include<cstdio> #include<cstring> #include<algorithm> #define INF 0x7fffffff #def…

3396: [Usaco2009 Jan]Total flow 水流 Time Limit: 1 Sec  Memory Limit: 128 MBSubmit: 179  Solved: 73[Submit][Status] Description   Input 第1行输入N,之后N行每行描述一条水管,前两个英文字母表示水管的两端(大小写字母是不一样的),后一个整数表示水管的流量,流量不会超过1000. Output 一个整数,表示总流量． Sample Input 5 A B 3 B C…

  当一个数据包到达网卡的时候,首先要经过内核Openvswitch.ko,流表Flow Table在内核中有一份,通过key查找内核中的flow table,即可以得到action,然后执行action之后,直接发送这个包,只有在内核无法查找到流表项的时候,才会到用户态查找用户态的流表.仅仅查找内核中flow table的情况被称为fast path.     第一步:从数据包中提取出key   实现函数为int ovs_flow_key_extract(const struct ip_tun…

luogu P1549 棋盘问题(2) 题解 题目描述 在\(N * N\)的棋盘上\((1≤N≤10)\),填入\(1,2,-,N^2\)共\(N^2\)个数,使得任意两个相邻的数之和为素数. 例如:当\(N=2\)时,有: 其相邻数的和为素数的有: \(1+2,1+4,4+3,2+3\) 当\(N=4\)时,一种可以填写的方案如下: 在这里我们约定:左上角的格子里必须填数字\(1\). 输入输出格式 输入格式: 一个数\(N\) 输出格式: 如有多种解,则输出第一行.第一列之和为最小的排列方…

P3128 [USACO15DEC]最大流Max Flow 题目描述 Farmer John has installed a new system of N-1N−1 pipes to transport milk between the NN stalls in his barn (2 \leq N \leq 50,0002≤N≤50,000), conveniently numbered 1 \ldots N1…N. Each pipe connects a pair of stalls,…

P3128 [USACO15DEC]最大流Max Flow 题目描述 Farmer John has installed a new system of  pipes to transport milk between the  stalls in his barn (), conveniently numbered . Each pipe connects a pair of stalls, and all stalls are connected to each-other via path…

OJ题号: BZOJ3996.洛谷2936.SPOJ-MTOTALF.SCU3353 思路: 题目的要求是将所有边合并成一条边,求合并后的流量. 实际上相当于直接求最大流. EdmondsKarp模板即可. #include<iostream> #include<vector> #include<queue> #include<cstring> #include<algorithm> ,E=,s=,t=,inf=0x7fffffff; inlin…

http://www.lydsy.com/JudgeOnline/problem.php?id=3396 裸的最大流跑过.. #include <cstdio> #include <cstring> #include <cmath> #include <string> #include <iostream> #include <algorithm> #include <queue> using namespace std;…

#include<cstdio> #include<cstring> #include<algorithm> #include<queue> using namespace std; #define INF 2147483647 #define MAXN 201 #define MAXM 1501 int v[MAXM],cap[MAXM],en,first[MAXN],next[MAXM]; int d[MAXN],cur[MAXN]; queue<…

最大流生动形象的板子,注意数组开大点 #include<iostream> #include<cstdio> #include<queue> #include<cstring> using namespace std; const int N=100,inf=1e9; int n=26,m,h[N],cnt=1,s=1,t=26,le[N],x; char s1[5],s2[5]; struct qwe { int ne,to,va; }e[N*N*2];…

裸的树上差分 因为要求点权所以在点上差分即可 #include <cstdio> #include <algorithm> #include <cstring> using namespace std; ; ; ; ,u[MAXN*],v[MAXN*],first[MAXN],next[MAXN*]; int cf[MAXN]; ]; int n,k; void addedge(int ux,int vx){ cnt++; u[cnt]=ux; v[cnt]=vx; n…

此类型题目有两种比较常见的做法:树链剖分和树上差分. 本题有多组修改一组询问,因此树上差分会比树链剖分优秀很多. 这里两种方法都进行介绍. 树链剖分和树上差分的本质都是将一颗树转换为一个区间,然后进行操作. 也就是说,先将一颗树变成区间,然后套用线段树/树状数组和差分. 树链剖分的具体流程不多加叙述,可以自己去翻它的模板题. 本题维护区间修改单点查询就OK了,最后输出答案的时候直接遍历所有节点取最大值. 1956ms,9805kb #include<iostream> #include<…

ACM Computer Factory Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 8944   Accepted: 3267   Special Judge Description As you know, all the computers used for ACM contests must be identical, so the participants compete on equal terms. Th…

当内核无法查找到流表项的时候,则会通过upcall来调用用户态ovs-vswtichd中的flow table. 会调用ofproto-dpif-upcall.c中的udpif_upcall_handler函数. static void * udpif_upcall_handler(void *arg) {     struct handler *handler = arg;     struct udpif *udpif = handler->udpif;       while (!latc…

连我自己把float和绝对定位,都称为脱离文档流,想想概念又不那么清晰,于是寻找了W3C资料来理解,才发觉不应该叫文档流. 资料 英文:https://www.w3.org/TR/CSS22/visuren.html#normal-flow 中文:http://w3help.org/zh-cn/kb/010/ PS:资料中文翻译为常规流,我觉得直译为普通流也行. 常规流 这个概念定义了什么东西,它决定了什么?它决定元素的布局方式,是基本的布局模式! 盒子模型 盒子模型,是DOM元素的抽象定义.盒…

题目链接 \(Click\) \(Here\) 非常有趣的一个题目. 关键结论:所有的单位费用应该被分配在流量最大的边上. 即:在保证最大流的前提下,使最大流量最小.这里我们采用二分的方法,每次判断让所有边的流量\(<=mid\)时是否依然有最大流,求得最小的最大流量\(*p\)即可. 为什么会有实数流量呢?其实我也不懂,不过这也造成这个题目需要把流量改成\(double\),有很多细节需要小心谨慎... #include <bits/stdc++.h> using namespace…