博客
关于我
POJ 2387 Til the Cows Come Home(Dijkstra优先队列)
阅读量:331 次
发布时间:2019-03-04

本文共 2391 字,大约阅读时间需要 7 分钟。

Bessie is out in the field and wants to get back to the barn to get as much sleep as possible before Farmer John wakes her for the morning milking. Bessie needs her beauty sleep, so she wants to get back as quickly as possible.

Farmer John’s field has N (2 <= N <= 1000) landmarks in it, uniquely numbered 1…N. Landmark 1 is the barn; the apple tree grove in which Bessie stands all day is landmark N. Cows travel in the field using T (1 <= T <= 2000) bidirectional cow-trails of various lengths between the landmarks. Bessie is not confident of her navigation ability, so she always stays on a trail from its start to its end once she starts it.
Given the trails between the landmarks, determine the minimum distance Bessie must walk to get back to the barn. It is guaranteed that some such route exists.
Input
Line 1: Two integers: T and N

Lines 2…T+1: Each line describes a trail as three space-separated integers. The first two integers are the landmarks between which the trail travels. The third integer is the length of the trail, range 1…100.

Output
Line 1: A single integer, the minimum distance that Bessie must travel to get from landmark N to landmark 1.
Sample Input
5 5
1 2 20
2 3 30
3 4 20
4 5 20
1 5 100
Sample Output
90
Hint
INPUT DETAILS:
There are five landmarks.
OUTPUT DETAILS:
Bessie can get home by following trails 4, 3, 2, and 1.

优先队列定义q就直接一个结构体就可以了,不要在写vector还是greater或者less了,写上去还麻烦,真的是伤心了。

#include 
#include
#include
#include
using namespace std;const int inf = 0x3f3f3f3f;struct node{ int d; int pos; };priority_queue
q;bool operator < (node a, node b){ return a.d > b.d;//权值小的边优先}int n , m;int e[2005][2005];int dis[2005];void dijkstra(int start){ int book[2005]; memset(book, 0, sizeof(book)); for (int i=1; i<=n; i++) if (i==start) dis[i]=0; else dis[i]=inf; node t; t.d=dis[start]; t.pos=start; q.push(t); while(!q.empty()){ t = q.top(); q.pop(); int x = t.pos; if(book[x]==1) continue; book[x] = 1; for(int j=1; j<=n; j++){ if(book[j]==0 && dis[j]>dis[x]+e[x][j]){ dis[j]=dis[x]+e[x][j]; node tt; tt.d=dis[j]; tt.pos=j; q.push(tt); } } } cout<
<
w){ e[u][v]=w; e[v][u]=w; } } dijkstra(1); } return 0;}

转载地址:http://lpnh.baihongyu.com/

你可能感兴趣的文章
mysql5.5最简安装教程
查看>>
mysql5.6 TIME,DATETIME,TIMESTAMP
查看>>
mysql5.6.21重置数据库的root密码
查看>>
Mysql5.6主从复制-基于binlog
查看>>
MySQL5.6忘记root密码(win平台)
查看>>
MySQL5.6的Linux安装shell脚本之二进制安装(一)
查看>>
MySQL5.6的zip包安装教程
查看>>
mysql5.7 for windows_MySQL 5.7 for Windows 解压缩版配置安装
查看>>
Webpack 基本环境搭建
查看>>
mysql5.7 安装版 表不能输入汉字解决方案
查看>>
MySQL5.7.18主从复制搭建(一主一从)
查看>>
MySQL5.7.19-win64安装启动
查看>>
mysql5.7.19安装图解_mysql5.7.19 winx64解压缩版安装配置教程
查看>>
MySQL5.7.37windows解压版的安装使用
查看>>
mysql5.7免费下载地址
查看>>
mysql5.7命令总结
查看>>
mysql5.7安装
查看>>
mysql5.7性能调优my.ini
查看>>
MySQL5.7新增Performance Schema表
查看>>
Mysql5.7深入学习 1.MySQL 5.7 中的新增功能
查看>>