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  • 洛谷 P4183 - [USACO18JAN]Cow at Large P(点分治)2021-09-10 22:33:07

    洛谷题面传送门 点分治 hot tea。 首先考虑什么样的点能够对以 \(u\) 为根的答案产生 \(1\) 的贡献。我们考虑以 \(u\) 为根对整棵树进行一遍 DFS。那么对于一个点 \(v\),我们记其 \(mn_v\) 为其子树内距离其最近的叶子,\(dep_v\) 为 \(u\) 到 \(v\) 的距离,那么如果 \(mn_v\ge dep_v

  • 浅析Java的fail-fast(快速失败)机制、COW优化策略、CopyOnWrite并发容器-读写分离思想2021-09-09 12:35:30

      在JDK的Collection中我们时常会看到类似于这样的话:   例如,ArrayList: 注意,迭代器的快速失败行为无法得到保证,因为一般来说,不可能对是否出现不同步并发修改做出任何硬性保证。 快速失败迭代器会尽最大努力抛出 ConcurrentModificationException。 因此,为提高这类迭代器的正确

  • Open Judge 4001 - Catch That Cow - BFS2021-09-03 16:01:17

      Catch That Cow 描述 农夫约翰已得知一头逃犯母牛的位置,他想立即抓住她。他从N (0 ≤ N ≤ 100,000)点开始,母牛在同一数字线上的K(0 ≤ K ≤ 100,000)点。 农夫约翰有两种交通方式:步行和心灵传送: 步行:FJ可以在一分钟内从任意点X移动到点X-1或X+1 传送:FJ可以在一分钟内从任意

  • 【8.24模拟赛T4.1328】【洛谷P1821】[USACO07FEB] Cow Party S【SPFA】2021-08-24 20:00:25

    分析 这题一眼就是裸的最短路嘛 一遍是从所有点到party点的最短路,另一遍是party点到所有点的最短路,对他们的和取max。 从10:42开始打,10:50就打完一遍过了。。。 上代码 #include<iostream> #include<cstdio> #include<algorithm> #include<queue> #include<cstring> using n

  • Silver Cow Party(最短路)2021-08-05 21:57:49

    题目 One cow from each of N farms (1 ≤ N ≤ 1000) conveniently numbered 1…N is going to attend the big cow party to be held at farm #X (1 ≤ X ≤ N). A total of M (1 ≤ M ≤ 100,000) unidirectional (one-way roads connects pairs of farms; road i require

  • Catch That Cow-抓住那头牛(BFS+队列)2021-07-31 09:03:46

     Catch That Cow  HDU - 2717  Farmer John has been informed of the location of a fugitive cow and wants to catch her immediately. He starts at a point N (0 ≤ N ≤ 100,000) on a number line and the cow is at a point K (0 ≤ K ≤ 100,000) on the same numbe

  • POJ - 2376 Cleaning Shifts2021-07-24 12:00:06

    Cleaning Shifts POJ - 2376 AYIT-2021 609暑假集训第一周上 搜索和贪心 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 cow working on cleaning things up and

  • Dirty_COW_ex2021-07-17 16:35:49

    8.1. A file’s content is a string "Hello World". When this file is mapped to memory (the entire file) using mmap(), and the memory address is stored in a variable map. Please describe what the following printf() statement prints out. char *addr

  • P3033 [USACO11NOV]Cow Steeplechase G(二分图最大独立集)2021-07-06 09:32:54

    P3033 [USACO11NOV]Cow Steeplechase G(二分图最大独立集) 将有冲突的线段建边,则题目变成求二分图的最大独立集。 最大独立集=结点数-最大匹配。 最小点覆盖=最大匹配。 采用匈牙利算法即可。 时间复杂度: O (

  • MIT6.S081学习总结-lab6:Copy-On-Write Fork2021-06-30 13:32:57

    lab6 也是虚拟内存的一种应用,主要实现fork时的写时复制copy-on-write功能。 问题 xv6中的fork()系统调用将所有父进程的用户空间内存复制到子进程中。如果父进程用户空间很大,复制可能需要很长时间。更糟糕的是,这种复制工作经常被浪费;例如,子进程中的fork()后跟exec()将导致子

  • 题解 P3045 【[USACO12FEB]牛券Cow Coupons】2021-06-28 22:34:27

    题目传送门 Desprition \(FJ\) 准备买一些新奶牛,市场上有 \(N\) 头奶牛、\(K\) 张优惠券,优惠劵可降价,每头奶牛只能使用一次优惠券。问知道花不超过 \(M\) 的钱最多可以买多少奶牛? Solution 贪心 + 优先队列 首先,根据经验, \(k\) 张优惠券肯定是尽量全用的…… 不要白不要嘛 优惠

  • [Usaco2006 Feb]Stall Reservations 专用牛棚2021-06-03 18:06:06

    Problem : 目录 Problem : Description Input Output Sample Input Sample Output   Time Limit: 1 Sec  Memory Limit: 128 MB Submit: 149  Solved: 66 [Submit][Status][Web Board] Description Oh those picky N (1 <= N <= 50,000) cows! They are so picky that

  • P6140 [USACO07NOV]Best Cow Line S2021-06-01 13:58:51

    难度:4 贪心问题,贪心策略要想对,这种一般都是从字典序全局考虑的,不能值考虑单独一个点, #include <bits/stdc++.h> #define fi first #define se second #define pb push_back #define all(x) (x).begin(), (x).end() using namespace std; typedef long long ll; typedef ve

  • [USACO09MAR]Cow Frisbee Team2021-05-29 19:02:45

     嘟嘟嘟   这个是一个很明显的dp,遇到这种倍数的问题的,就令dp[i][j]表示选到了第 i 只牛(不是选了 i 只牛),sum(Ri) % f == j 的方案数,则,     dp[i][j] = dp[i - 1][j] + dp[i - 1][(j + f - a[i] % f) % f] 等式右边第一项表示第 i 只牛不选,第二项表示第 i 只牛选了,j + f 是为

  • P2891 [USACO07OPEN]吃饭Dining(最大流+拆点)2021-05-20 22:55:06

    题目描述 Cows are such finicky eaters. Each cow has a preference for certain foods and drinks, and she will consume no others. Farmer John has cooked fabulous meals for his cows, but he forgot to check his menu against their preferences. Although he might no

  • 洛谷 P2888 [USACO07NOV]牛栏Cow Hurdles2021-05-20 22:54:18

    题目戳   题目描述 Farmer John wants the cows to prepare for the county jumping competition, so Bessie and the gang are practicing jumping over hurdles. They are getting tired, though, so they want to be able to use as little energy as possible to jump over t

  • Protecting the Flowers 牛客题解2021-05-19 12:31:33

    Protecting the Flowers 题目链接:传送门 链接:https://ac.nowcoder.com/acm/problem/25043 来源:牛客网 Farmer John went to cut some wood and left N (2 ≤ N ≤ 100,000) cows eating the grass, as usual. When he returned, he found to his horror that the cluster of

  • 使用友元函数重载运算符2021-05-12 19:31:03

    其他文件不变 Cow.h #pragma once class Pork; class Sheep; class Cow{ //牛 public: Cow(int weight = 0); // 用友元函数实现运算符重载 friend Pork operator+(const Cow &c1, const Cow &c2); friend Pork operator+(const Sheep &s1, const Cow &c2); private:

  • [bzoj3939_Usaco2015 Feb]Cow Hopscotch(线段树维护DP)2021-05-06 21:59:41

                   \;\;\;\;\;\;\; 今天晚上,想到自己的线段树专题中的题还未码完。                \;\;\;\;\;\;\;

  • 洛谷 P1522 [USACO2.4]牛的旅行 Cow Tours (最短路,floyd)2021-05-01 16:34:11

    传送门 分析:对于给出的邻接矩阵,用并查集维护牧场,并求两点的距离,然后对所有点跑一个floyd(因为只有连通的点我们才求了距离,所以可以直接对所有点跑),对于一个牧场,我们可以求出它里面每个点到其他点的最远距离,以及牧场的直径,那么我们再去枚举任意两个点,如果它们不在一个

  • Silver Cow Party java优先队列实现2021-04-30 17:01:58

    题目链接:Silver Cow Party 两次迪杰斯特拉即可。这次使用了优先队列。 import java.io.BufferedReader; import java.io.InputStreamReader; import java.util.*; public class Main { public static void main(String[] args) throws Exception { BufferedReader br

  • 洛谷P1522 牛的旅行 Cow Tours2021-04-18 02:02:45

    链接 题意: 给定一片牧区,一片所有连通的牧区称为一个牧场。要求在两个不连通的牧场的牧区之间添加一条路径,使得两个牧场连接,并且求得再老牧场和新牧场里面的牧场直径最大值的最小值是多少。 思路: 首先根据题意我们得知我们需要求得每个牧场的直径的大小,即牧场里面的牧区之间的最短

  • P2419 [USACO08JAN]Cow Contest S2021-04-17 17:03:27

    传递闭包裸题。 如果一头奶牛和其他\(n-1\)头奶牛的大小关系都确定了,那么该奶牛的排名可唯一确定。 或者说,比它强的奶牛的数量加上比它弱的奶牛的数量等于\(n-1\),就可唯一确定该奶牛的名次。 const int N=110; bool g[N][N]; int n,m; void floyd() { for(int k=1;k<=n;k++)

  • 白书中的 区间贪心例题。POJ 2376,1328,3190(各种区间分布的最大最小问题,优先队列)2021-04-10 20:02:26

    POJ 2376   Cleaning Shifts Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 51535   Accepted: 12380 Description Farmer John is assigning some of his N (1 <= N <= 25,000) cows to do some cleaning chores around the barn. He alway

  • P1588 [USACO07OPEN]Catch That Cow S2021-04-05 16:05:01

    人生第一道做出来的BFS题,这道题很适合入门的BFS 个人解析   通过这道题,我对BFS认识多点理解,   BFS的过程其实可以看成一棵树,树的孩子就是我们采取的不同方式,本题就可以看成一棵三叉树   注意边界情况,不要越界      #include<bits/stdc++.h> using namespace std; queue<

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