CF721C. Journey[DP DAG]
3 seconds
256 megabytes
standard input
standard output
Recently Irina arrived to one of the most famous cities of Berland — the Berlatov city. There are n showplaces in the city, numbered from 1 to n, and some of them are connected by one-directional roads. The roads in Berlatov are designed in a way such that there are nocyclic routes between showplaces.
Initially Irina stands at the showplace 1, and the endpoint of her journey is the showplace n. Naturally, Irina wants to visit as much showplaces as she can during her journey. However, Irina's stay in Berlatov is limited and she can't be there for more than T time units.
Help Irina determine how many showplaces she may visit during her journey from showplace 1 to showplace n within a time not exceeding T. It is guaranteed that there is at least one route from showplace 1 to showplace n such that Irina will spend no more than Ttime units passing it.
The first line of the input contains three integers n, m and T (2 ≤ n ≤ 5000, 1 ≤ m ≤ 5000, 1 ≤ T ≤ 109) — the number of showplaces, the number of roads between them and the time of Irina's stay in Berlatov respectively.
The next m lines describes roads in Berlatov. i-th of them contains 3 integers ui, vi, ti (1 ≤ ui, vi ≤ n, ui ≠ vi, 1 ≤ ti ≤ 109), meaning that there is a road starting from showplace ui and leading to showplace vi, and Irina spends ti time units to pass it. It is guaranteed that the roads do not form cyclic routes.
It is guaranteed, that there is at most one road between each pair of showplaces.
Print the single integer k (2 ≤ k ≤ n) — the maximum number of showplaces that Irina can visit during her journey from showplace 1 to showplace n within time not exceeding T, in the first line.
Print k distinct integers in the second line — indices of showplaces that Irina will visit on her route, in the order of encountering them.
If there are multiple answers, print any of them.
4 3 13
1 2 5
2 3 7
2 4 8
3
1 2 4
6 6 7
1 2 2
1 3 3
3 6 3
2 4 2
4 6 2
6 5 1
4
1 2 4 6
5 5 6
1 3 3
3 5 3
1 2 2
2 4 3
4 5 2
3
1 3 5
题意:单向,没有回路,没有重边自环,限制时间,求1到n最多经过几个点,并输出这些点任意方案
因为没有环,又保证1和n连通,一开始想树形DP,并不好做,然后发现这是有向边
突然发现,这不就是有向无环图,有向无环图DAG的最短路最长路可以用DP来做,扩展一下应该也可以
f[i][j]表示从i到n经过j个点的时间 PS:因为忘判vis TLE一次
//
// main.cpp
// c
//
// Created by Candy on 9/30/16.
// Copyright © 2016 Candy. All rights reserved.
// #include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>
#include <string>
using namespace std;
const int N=,M=,INF=1e9+;
inline int read(){
char c=getchar();int x=,f=;
while(c<''||c>''){if(c=='-')f=-;c=getchar();}
while(c>=''&&c<=''){x=x*+c-'';c=getchar();}
return x;
}
int n,m,T,u,v,w;
struct edge{
int v,w,ne;
}e[M<<];
int h[N],cnt=;
void ins(int u,int v,int w){
cnt++;
e[cnt].v=v;e[cnt].w=w;e[cnt].ne=h[u];h[u]=cnt;
}
int f[N][N],vis[N];
void dp(int u){
if(u==n) return;
int child=;
if(vis[u]) return;
vis[u]=;
for(int i=h[u];i;i=e[i].ne){
child++;
int v=e[i].v,w=e[i].w;
dp(v);
for(int j=;j<=n;j++) if(f[v][j-]<INF)
f[u][j]=min(f[u][j],f[v][j-]+w);
}
}
void print(int u,int d){
printf("%d ",u);
for(int i=h[u];i;i=e[i].ne){
int v=e[i].v,w=e[i].w;
if(f[v][d-]<INF&&f[u][d]==f[v][d-]+w) {print(v,d-);break;}
}
}
int main(int argc, const char * argv[]) {
n=read();m=read();T=read();
for(int i=;i<=m;i++){
u=read();v=read();w=read();
ins(u,v,w);
}
memset(f,,sizeof(f));
f[n][]=;
dp();
int num=;
for(int i=n;i>=;i--)
if(f[][i]<=T) {num=i;break;}
printf("%d\n",num);
print(,num);
return ;
}
CF721C. Journey[DP DAG]的更多相关文章
- 拓扑排序+DP CF721C Journey
CF721C Journey 给出一个\(n\)个点\(m\)条边的有向无环图. 问从\(1\)到\(n\),在距离不超过\(k\)的情况下最多经过多少点,并输出一个方案. \(topo\)+\(DP ...
- NYOJ16|嵌套矩形|DP|DAG模型|记忆化搜索
矩形嵌套 时间限制:3000 ms | 内存限制:65535 KB 难度:4 描述 有n个矩形,每个矩形可以用a,b来描述,表示长和宽.矩形X(a,b)可以嵌套在矩形Y(c,d)中当且仅当a& ...
- 「BZOJ1924」「SDOI2010」 所驼门王的宝藏 tarjan + dp(DAG 最长路)
「BZOJ1924」[SDOI2010] 所驼门王的宝藏 tarjan + dp(DAG 最长路) -------------------------------------------------- ...
- CF #374 (Div. 2) C. Journey dp
1.CF #374 (Div. 2) C. Journey 2.总结:好题,这一道题,WA,MLE,TLE,RE,各种姿势都来了一遍.. 3.题意:有向无环图,找出第1个点到第n个点的一条路径 ...
- codeforces 721C C. Journey(dp)
题目链接: C. Journey time limit per test 3 seconds memory limit per test 256 megabytes input standard in ...
- Codeforces Round #374 (Div. 2) C. Journey DP
C. Journey 题目连接: http://codeforces.com/contest/721/problem/C Description Recently Irina arrived to o ...
- Codeforce 721C DP+DAG拓扑序
题意 在一个DAG上,从顶点1走到顶点n,路径上需要消费时间,求在限定时间内从1到n经过城市最多的一条路径 我的做法和题解差不多,不过最近可能看primer看多了,写得比较复杂和结构化 自己做了一些小 ...
- Codeforces Round #374 (Div. 2) C. Journey —— DP
题目链接:http://codeforces.com/contest/721/problem/C C. Journey time limit per test 3 seconds memory lim ...
- VK Cup 2015 - Qualification Round 1 A. Reposts [ dp DAG上最长路 ]
传送门 A. Reposts time limit per test 1 second memory limit per test 256 megabytes input standard input ...
随机推荐
- javascript对象继承详解
问题 比如我们有一个"动物"对象的构造函数. function animal() { this.type = '动物'; } 还有一个"猫"对象的构造函数. f ...
- HTML标签的嵌套规则
我在平时在写html文档的时候,发现不太清楚标签之间的嵌套规则,经常是想到什么标签就用那些,后来发现有些标签嵌套却是错误的.通过网上找资料,了解了html标签的嵌套规则. 一.HTML 标签包括 块级 ...
- SharePoint Online 创建门户网站系列之定制栏目
前 言 SharePoint Online自带的库就带有二级页面和详细页面,也就是Allitems页面和DispForm页面,但是实在不够美观,尤其对于门户网站这一企业门面来说,更是无法接受. 下面, ...
- [SharePoint] SharePoint 错误集 1
1. Delete a site collection · Run command : Remove-SPSite –Identity http://ent132.sharepoint.hp.com/ ...
- OC中的深拷贝与浅拷贝
深拷贝(deep copy)与浅拷贝(shallow copy)的定义一直是有争论的. 一种理解是: 所谓的浅拷贝, 就是不完全的拷贝 NSString *s = @"123"; ...
- OC中的protocol
一. 简单使用 1. 基本用途 可以用来声明一大堆方法(不能声明成员变量) 只要某个类遵守了这个协议,就相当于拥有这个协议中的所有方法声明 只要父类遵守了某个协议,就相当于子类也遵守了 2. 格式 协 ...
- Android Build Error(1)
Type 1 —— Build Path Problem : **.jar包文件缺失 1.在Android项目根目录下新建一个libs文件夹: 2.把你需要的导入的第三方Jar包复制进这个目录: 3. ...
- python中列表、元组、字典内部功能介绍
一.列表(list) 常用功能的介绍:
- 深入理解JavaScript系列(1):编写高质量JavaScript代码的基本要点
深入理解JavaScript系列(1):编写高质量JavaScript代码的基本要点 2011-12-28 23:00 by 汤姆大叔, 139489 阅读, 119 评论, 收藏, 编辑 才华横溢的 ...
- 安装使用ubuntu问题汇总
很早以前就安装了ubuntu系统,可是一直没怎么用,也没有深入研究.这两天重装了一下windows,顺带着也重新装了一遍最新的ubuntu14.04.期间碰到了不少问题,一个个解决也花费了不少时间.所 ...