求出家到其他点的最短路径,题目的条件变成了u->v不是回头路等价于d[u]>d[v]. 然后根据这个条件建DAG图,跑dp统计方案数,dp[u] = sum(dp[v]). #include<bits/stdc++.h> using namespace std; , maxm = ; struct Edge { int v,w,nxt; }; #define PB push_back vector<Edge> edges; vector<int> G[max…

Jimmy experiences a lot of stress at work these days, especially since his accident made working difficult. To relax after a hard day, he likes to walk home. To make things even nicer, his office is on one side of a forest, and his house is on the ot…

题目: gbn最近打算穿过一个森林,但是他比较傲娇,于是他决定只走一些特殊的道路,他打算只沿着满足如下条件的(A,B)道路走:存在一条从B出发回家的路,比所有从A出发回家的路径都短.你的任务是计算一共有多少条不同的回家路径.其中起点的编号为1,终点的编号为2. 分析: 先求出每个点到终点的距离,根据题目要求找d[u]>d[v]的路径(u,v)走,计算路径数即可. 代码如下: #include<cstdio> #include<cstdlib> #include<cstr…

题目大意:n个点,m条边的无向图.一个人从起点到终点按照下面的走法:从A走向B当A到终点的最小距离比B到终点的最小距离大时.问从起点到终点有多少路径方案. 题目分析:先用dijkstra预处理出终点到每个点的最短路,然后将满足行走条件的A.B(除行走条件外,还要满足一个前提,即A.B之间要有边)用一条有向边连起来(A->B),得到一个DAG,动态规划解决. 代码如下: # include<iostream> # include<cstdio> # include<vec…

题目给一张有向图,问从起点1到终点2沿着合法的路走有种走法,合法的路指从u到v的路,v到终点的距离严格小于u到终点的距离. 先SPFA预处理出所有合法的路,然后这些路肯定形成一个DAG,然后DP一下就OK了,d[u]表示u到终点2的方案数. #include<cstdio> #include<cstring> #include<queue> using namespace std; #define INF (1LL<<60) #define MAXN 111…

Problem    UVA - 10917 - Walk Through the Forest Time Limit: 3000 mSec Problem Description Jimmy experiences a lot of stress at work these days, especially since his accident made working difficult. To relax after a hard day, he likes to walk home. To…

A Walk Through the Forest Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 10172    Accepted Submission(s): 3701 Problem Description Jimmy experiences a lot of stress at work these days, especial…

A Walk Through the Forest Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 8850    Accepted Submission(s): 3267 Problem Description Jimmy experiences a lot of stress at work these days, especiall…

A Walk Through the Forest Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 5679    Accepted Submission(s): 2086 Problem Description Jimmy experiences a lot of stress at work these days, especiall…

A Walk Through the Forest Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 4383    Accepted Submission(s): 1573 Problem Description Jimmy experiences a lot of stress at work these days, especiall…

A Walk Through the Forest Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 9081 Accepted Submission(s): 3353 Problem Description Jimmy experiences a lot of stress at work these days, especially sin…

题目链接:https://vjudge.net/problem/UVA-10917 题目意思:Jimmy下班回家要闯过一下森林,劳累一天后在森林中散步是非常惬意的事,所以他打算每天沿着一条不同的路径回家,欣赏不同的风景,但他也不太想太晚回家,因此他不打算走回头路.换句话来说,他只会沿着如下条件的道路(A,B)走:存在一条从B出发回家的路径,比所有从A出发回家的路径都要短.我们的任务是要找出一共有有多少条不同的回家路径,家的编号是2,公司的编号是1. 题目思路:最短路+dp,我们现在考虑如何dp,…

A Walk Through the Forest 题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=1142 Description Jimmy experiences a lot of stress at work these days, especially since his accident made working difficult. To relax after a hard day, he likes to walk home. T…

A Walk Through the Forest Time Limit:1000MS  Memory Limit:65536K Total Submit:48 Accepted:15 Description Jimmy experiences a lot of stress at work these days, especially since his accident made working difficult. To relax after a hard day, he likes t…

A Walk Through the Forest Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 118 Accepted Submission(s): 57   Problem Description Jimmy experiences a lot of stress at work these days, especially sinc…

Jimmy experiences a lot of stress at work these days, especially since his accident made working difficult. To relax after a hard day, he likes to walk home. To make things even nicer, his office is on one side of a forest, and his house is on the ot…

A Walk Through the Forest Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 5306    Accepted Submission(s): 1939 Problem Description Jimmy experiences a lot of stress at work these days, especiall…

A Walk Through the Forest Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 7733    Accepted Submission(s): 2851 Problem Description Jimmy experiences a lot of stress at work these days, especiall…

A Walk Through the Forest Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 4603    Accepted Submission(s): 1671 Problem DescriptionJimmy experiences a lot of stress at work these days, especially…

A Walk Through the Forest Time Limit : 2000/1000ms (Java/Other)   Memory Limit : 65536/32768K (Java/Other) Total Submission(s) : 3   Accepted Submission(s) : 1 Problem Description Jimmy experiences a lot of stress at work these days, especially since…

B. A Walk Through the Forest Time Limit: 1000ms Memory Limit: 32768KB 64-bit integer IO format: %I64d      Java class name: Main   Jimmy experiences a lot of stress at work these days, especially since his accident made working difficult. To relax af…

题目链接:acm.hdu.edu.cn/showproblem.php?pid=1142 Problem Description Jimmy experiences a lot of stress at work these days, especially since his accident made working difficult. To relax after a hard day, he likes to walk home. To make things even nicer,…

Hunter Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 2014    Accepted Submission(s): 615 Problem Description One day, a hunter named James went to a mysterious area to find the treasures. Jame…

BZOJ_1003_[ZJOI2006]物流运输_最短路+dp 题意:http://www.lydsy.com/JudgeOnline/problem.php?id=1003 分析: 这种一段一段的显然要用dp求. f[i]表示到第i天为止的最小花销.转移有f[i]=min{f[j-1]+cost[j][i]*(i-j+1)+k}; 其中cost[i][j]表示从i到j天的最短路长度,spfa预处理出来. 代码: #include <stdio.h> #include <string.h…

任意门:http://poj.org/problem?id=3635 Full Tank? Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 8388   Accepted: 2734 Description After going through the receipts from your car trip through Europe this summer, you realised that the gas pri…

题目链接 Solution 非正解 似乎比较蛇啊,先个一个部分分做法,最短路+\(DP\). 在求最短路的堆或者队列中存储元素 \(dis_{i,j}\) 代表 \(i\) 这个节点,走了 \(j\) 条边的距离. 然后跑堆优化 \(Dijkstra\) 或者 SPFA 即可. 复杂度 \(O(N*nlog(n))\). 其中 \(N\) 代表要走的边条数, \(n\) 代表节点数 . 但是这题 \(N\) 有 \(10^6\) ... 洛谷上可以过掉 \(49\) 分. 不过只要 \(N\)…

思路:最短路+DP 提交:1次 题解: $f[i]$表示到第$i$天的最小代价,我们可以预先处理出$i,j$两天之间(包括$i,j$)都可通行的最短路的代价记做$s[i][j]$,然后有$f[i]=min(f[i],f[j]+s[j+1][i]*(i-j)+W);$ #include<cstdio> #include<iostream> #include<cstring> #include<queue> #define ull unsigned long l…

bzoj1003物流运输 题目描述 物流公司要把一批货物从码头A运到码头B.由于货物量比较大,需要n天才能运完.货物运输过程中一般要转停好几个码头.物流公司通常会设计一条固定的运输路线,以便对整个运输过程实施严格的管理和跟踪.由于各种因素的存在,有的时某个码头会无法装卸货物.这时候就必须修改运输路线,让货物能够按时到达目的地.但是修改路线是一件十分麻烦的事情,会带来额外的成本.因此物流公司希望能够订一个n天的运输计划,使得总成本尽可能地小. 输入格式 第一行是四个整数n(1<=n<=100).…

最短路+dp思路:nuoyanli 520 Let's play computer game 输入样例1: 10 15 0 1 0 1 1 8 0 0 1 1 4 8 1 1 1 5 4 0 2 3 5 9 1 1 4 0 6 0 1 1 7 3 1 1 2 8 3 1 1 2 2 5 0 2 2 2 1 1 1 1 1 5 0 1 3 1 4 0 1 1 9 7 1 1 3 3 1 0 2 5 6 3 1 2 1 5 3   输出样例1: Time = 6: 5 => 4 => 8 =>…

题目链接 题意 :办公室编号为1,家编号为2,问从办公室到家有多少条路径,当然路径要短,从A走到B的条件是,A到家比B到家要远,所以可以从A走向B . 思路 : 先以终点为起点求最短路,然后记忆化搜索. #include <cstdio> #include <queue> #include <cstring> #include <iostream> << ; using namespace std ; int N,M ; ][] ,pre[],d…