POJ 2387 最短路Dijkstra算法
2015-06-19 15:14
253 查看
Til the Cows Come Home
Description
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
Sample Output
Hint
INPUT DETAILS:
There are five landmarks.
OUTPUT DETAILS:
Bessie can get home by following trails 4, 3, 2, and 1.
Source
USACO 2004 November
Time Limit: 1000MS | Memory Limit: 65536K | |
Total Submissions: 33607 | Accepted: 11383 |
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.
Source
USACO 2004 November
#include<iostream> #include<cstdio> #include<cstring> #include<algorithm> using namespace std; #define inf 0x3f3f3f3f #define N 1005 int map ,d ,s ; int main() { int t,n,a,b,val; while(~scanf("%d%d",&t,&n)) { memset(map,inf,sizeof(map)); memset(s,0,sizeof(s)); for(int i=1;i<=n;i++) { d[i]=i; } while(t--) { scanf("%d%d%d",&a,&b,&val); if(val<map[a][b]) map[a][b]=map[b][a]=val; } for(int i=1;i<=n;i++) d[i]=(i==1?0:inf); for(int i=1;i<=n;i++) { int x,mi=inf; for(int j=1;j<=n;j++) { if(!s[j]&&d[j]<=mi) { mi=d[x=j]; } } s[x]=1; for(int j=1;j<=n;j++) { d[j]=min(d[j],d[x]+map[x][j]); } } printf("%d\n",d ); } return 0; }
相关文章推荐
- STM8S003F使用IO口模拟串口(三)使用中断方式发送和接收数据
- VS2010快捷键大全
- CMake 手册详解(七)
- 动态规划——算法总结(三)
- 动态规划——算法总结(三)
- c# win form 显示支付宝二维码图片
- 基于libVLC的视频播放器
- CMake 手册详解(六)
- [CSS] 限制字符串长度,自动截断。
- 如何有效减少网页加载时间?(转)
- 函数调用
- 计算1到100000中出现93的次数
- POJ 1006 && HDU 1370 Biorhythms(水~)
- [PHP] 用AppServ一步到位安装PHP服务器
- C语言-EOF和feof()判断文件结尾的区别
- Android TextView drawableLeft 在代码中实现
- 第02章
- jenkins 插件开发-简单demo
- 最简单的基于 DirectShow 的视频播放器
- OSX现新漏洞!用户密码可遭大范围泄露