Evacuation Plan Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 4617   Accepted: 1218   Special Judge Description The City has a number of municipal buildings and a number of fallout shelters that were build specially to hide municipal w…

题意:给定一个最小费用流的模型,根据给定的数据判定是否为最优解,如果不为最优解则给出一个比给定更优的解即可.不需要得出最优解. 解法:由给定的数据能够得出一个残图,且这个图满足了最大流的性质,判定一个残图是否满足最小费用最大流的判定依据类比于最大流中的层次图的构建,此时只需要判定图中是否存在负环即可.在写的过程中由于图中的编号和抽象了之后的编号有一个变换关系,所以处理要小心,一开始直接写了个最小费用最大流,通过费用来判定是否为最优TLE.找负环的时候,该题宜从汇点开始遍历,因为源点发出的边肯定全…

Evacuation Plan Time Limit: 1000MSMemory Limit: 65536KTotal Submissions: 5665Accepted: 1481Special Judge 题目链接:http://poj.org/problem?id=2175 Description: The City has a number of municipal buildings and a number of fallout shelters that were build sp…

跟 UVa 1474 - Evacuation Plan 一个题,但是在杭电上能交过,在UVa上交不过……不知道哪里有问题…… 将施工队位置和避难所位置排序. dp[i][j] 代表前 i 个避难所收留前 j 个施工队. dp[i][j] = min( dp[i - 1][j - 1], dp[i][j - 1] ) + abs( b[i] - a[j] ); 内存卡的比较死,要用滚动数组,并且记录路径的path[i][j]只能用bool型.MLE了四五次OTL…… #include <cstd…

"Evacuation Plan" Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100002 Description The City has a number of municipal buildings and a number of fallout shelters that were build specially to hide municipal workers in case …

http://poj.org/problem?id=2175 Evacuation Plan Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 3256   Accepted: 855   Special Judge Description The City has a number of municipal buildings and a number of fallout shelters that were build…

Evacuation Plan Time Limit: 1000ms Memory Limit: 65536KB This problem will be judged on PKU. Original ID: 217564-bit integer IO format: %lld      Java class name: Main   The City has a number of municipal buildings and a number of fallout shelters th…

题目给了一个满足最大流的残量网络,判断是否费用最小. 如果残量网络中存在费用负圈,那么不是最优,在这个圈上增广,增广1的流量就行了. 1.SPFA中某个点入队超过n次,说明存在负环,但是这个点不一定在负环上. 2.这个负环可能包括汇点t,所以构建残量网络的时候也要考虑防空洞到t上的容量. //#pragma comment(linker, "/STACK:1024000000,1024000000") #include<cstdio> #include<cstring…

---恢复内容开始--- 题意略. 这题在poj直接求最小费用会超时,但是题意也没说要求最优解. 根据线圈定理,如果一个跑完最费用流的残余网络中存在负权环,那么顺着这个负权环跑流量为1那么会得到更小的费用. 关键是坑在找环的起点.其实看了代码之后发现的确不难... #include<stdio.h> #include<queue> #include<string.h> #define MAXN 300 #define MAXM 30002*4 #define INF 1…

题意:有一条公路,上面有n个施工队,要躲进m个避难所中,每个避难所中至少有一个施工队,躲进避难所的花费为施工队与避难所的坐标差的绝对值,求最小花费及策略. 解法:将施工队和避难所按坐标排序,可以看出有下列递推关系,dp[i][j]表示前j个施工队进入前i个避难所的花费,则有dp[i][j] = min(dp[i][j - 1], dp[i - 1][j - 1]) + |a[j] - b[i]|.由于每个避难所至少有一个施工队,所以j从i开始遍历.滚动数组优化. 用path记录当前施工队进入的是…

题目链接 题意:一个城市有n座行政楼和m座避难所,现发生核战,要求将避难所中的人员全部安置到避难所中,每个人转移的费用为两座楼之间的曼哈顿距离+1,题目给了一种方案,问是否为最优方案,即是否全部的人员转移费用之和最小?若不是,输出SUBOPTIMAL,之后输出转移矩阵Ei,j.即第i座行政楼中Ei,j个人转移到第j座避难所;输出的不必是最优转移方案,只要比题解的sum小即可: 思路:直接建一个残量网络,即按照开始建的原图跑完最小费用流之后剩下的网络,行政楼和避难所之间的原图连边正向容量为inf,…

POJ \(Description\) \(n\)个建筑物,每个建筑物里有\(a_i\)个人:\(m\)个避难所,每个避难所可以容纳\(b_i\)个人. 给出每个建筑物及避难所的坐标,任意两点间的距离为它们的曼哈顿距离\(+1\). 现在给出一个分配方案(\(g[i][j]\)表示第\(i\)个建筑物去第\(j\)个避难所的人数),问是否存在所有人移动的距离之和比当前更小的方案.如果存在,输出任意一组更小的方案. \(n,m\leq100\) \(Solution\) 直接跑费用流会T,但是也没…

题意:有N栋楼,每栋楼有\(val_i\)个人要避难,现在有M个避难所,每个避难所的容量为\(cap_i\),每个人从楼i到避难所j的话费是两者的曼哈顿距离.现在给出解决方案,问这个解决方案是否是花费最小的,若不是,则给出比这个更优的解. 分析:若只是要我们求一个最优解的话就用费用流做.现在要求判断是否最优,那么就是当前这张图中是否最短路还能被更新. 首先需要根据给定的解决方案重现这个状态下的残余网,其实只需要加入必要的弧即可:对与任意的楼与避难所(i,j),建边,费用为其距离;若i->j有流量…

http://poj.org/problem?id=2175 题意:有n个楼,m个防空洞,每个楼有一个坐标和一个人数B,每个防空洞有一个坐标和容纳量C,从楼到防空洞需要的时间是其曼哈顿距离+1,现在给出一个方案,问该方案是否是让所有人到防空洞避难的花费时间最少的方案,如果不是,输出一个最佳方案. 思路:一开始直接用最小费用最大流,超时了.学习了一下消圈算法. 如果不考虑得到最小费用,只需要考虑当前是否最小费用的话,那么是可以用消圈算法来解决的. 结论:当没有负圈的时候,当前的费用是最小的. 因此…

Time Limit: 1000MS Memory Limit: 65536K Special Judge Description The City has a number of municipal buildings and a number of fallout shelters that were build specially to hide municipal workers in case of a nuclear war. Each fallout shelter has a l…

题目链接 https://icpcarchive.ecs.baylor.edu/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=2988 problem Description Flatland government is building a new highway that will be used to transport weapons from its main weapon plan…

Evacuation Plan Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 3384   Accepted: 888   Special Judge Description The City has a number of municipal buildings and a number of fallout shelters that were build specially to hide municipal wo…

Ombrophobic Bovines Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 18623   Accepted: 4057 Description FJ's cows really hate getting wet so much that the mere thought of getting caught in the rain makes them shake in their hooves. They h…

FQ找来,可能历史比较悠久了,慢慢看. 原文连接:http://www.impactinterview.com/2009/10/140-google-interview-questions/ Google Interview Questions: Product Marketing Manager Why do you want to join Google? What do you know about Google’s product and technology? If you are P…

Ombrophobic Bovines Time Limit: 1000MSMemory Limit: 65536K Total Submissions: 14519Accepted: 3170 Description FJ's cows really hate getting wet so much that the mere thought of getting caught in the rain makes them shake in their hooves. They have de…

Ombrophobic Bovines Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 16539 Accepted: 3605 Description FJ's cows really hate getting wet so much that the mere thought of getting caught in the rain makes them shake in their hooves. They have…

                     Ombrophobic Bovines Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 18205   Accepted: 3960 Description FJ's cows really hate getting wet so much that the mere thought of getting caught in the rain makes them shake in…

Description FJ's cows really hate getting wet so much that the mere thought of getting caught in the rain makes them shake in their hooves. They have decided to put a rain siren on the farm to let them know when rain is approaching. They intend to cr…

最短路问题此类问题类型不多,变形较少 POJ 2449 Remmarguts' Date(中等)http://acm.pku.edu.cn/JudgeOnline/problem?id=2449题意:经典问题:K短路解法:dijkstra+A*(rec),方法很多相关:http://acm.pku.edu.cn/JudgeOnline/showcontest?contest_id=1144该题亦放在搜索推荐题中 POJ 3013 - Big Christmas Tree(基础)http://ac…

某猎头收集了140多个Google的面试题,主要是下面这些职位的. Product Marketing Manager Product Manager Software Engineer Software Engineer in Test Quantitative Compensation Analyst Engineering Manager AdWords Associate 这 篇Blog例举了Google用来面试下面这几个职位的面试题.很多不是很容易回答,不过都比较经典与变态,是 Goo…

转自——http://blog.csdn.net/qwe20060514/article/details/8112550 =============================以下是最小生成树+并查集======================================[HDU]1213   How Many Tables   基础并查集★1272   小希的迷宫   基础并查集★1325&&poj1308  Is It A Tree?   基础并查集★1856   More i…

一道水题WA了这么多次真是.... 统考终于完 ( 挂 ) 了...可以好好写题了... 先floyd跑出各个点的最短路 , 然后二分答案 m , 再建图. 每个 farm 拆成一个 cow 点和一个 shelter 点, 然后对于每个 farm x : S -> cow( x ) = cow( x ) 数量 , shelter( x ) -> T = shelter( x ) 容量 ; 对于每个dist( u , v ) <= m 的 cow( u ) -> shelter( v…

-----------------------------最优化问题------------------------------------- ----------------------常规动态规划  SOJ1162 I-Keyboard  SOJ1685 Chopsticks SOJ1679 Gangsters SOJ2096 Maximum Submatrix  SOJ2111 littleken bg SOJ2142 Cow Exhibition  SOJ2505 The County…

Ombrophobic Bovines Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 19359   Accepted: 4186 Description FJ's cows really hate getting wet so much that the mere thought of getting caught in the rain makes them shake in their hooves. They h…

=============================以下是最小生成树+并查集====================================== [HDU] How Many Tables 基础并查集★ 小希的迷宫 基础并查集★ &&poj1308 Is It A Tree? 基础并查集★ More is better 基础并查集★ Constructing Roads 基础最小生成树★ 畅通工程 基础并查集★ 还是畅通工程 基础最小生成树★ 畅通工程 基础最小生成树★ 畅通…