poj2502Subway(SPFA)
来源:互联网 发布:人工智能有哪些刊物 编辑:程序博客网 时间:2024/06/08 19:27
题目链接:
huangjing
分析:
首先说我做这题在哪里出现误区。。
【1】 首先一条线路上的地铁站只有相邻的两站可以到达,比如一站和3站就不能直接到达,所以建边的时候应该用步行建边。。。。还有就是数据给的同一条线路上的地铁站的纵坐标都相同,所以比较误导人。。。
【2】最后的结果要四舍五入,就是精度的问题要注意。。。
【3】还有一个小知识 double类型的不能初始化为-1。。。
这个题没a出来,哎 太忧伤了。。。
【2】最后的结果要四舍五入,就是精度的问题要注意。。。
【3】还有一个小知识 double类型的不能初始化为-1。。。
这个题没a出来,哎 太忧伤了。。。
题目:
Language:
Subway
Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 6123 Accepted: 1991
Description
You have just moved from a quiet Waterloo neighbourhood to a big, noisy city. Instead of getting to ride your bike to school every day, you now get to walk and take the subway. Because you don't want to be late for class, you want to know how long it will take you to get to school.
You walk at a speed of 10 km/h. The subway travels at 40 km/h. Assume that you are lucky, and whenever you arrive at a subway station, a train is there that you can board immediately. You may get on and off the subway any number of times, and you may switch between different subway lines if you wish. All subway lines go in both directions.
You walk at a speed of 10 km/h. The subway travels at 40 km/h. Assume that you are lucky, and whenever you arrive at a subway station, a train is there that you can board immediately. You may get on and off the subway any number of times, and you may switch between different subway lines if you wish. All subway lines go in both directions.
Input
Input consists of the x,y coordinates of your home and your school, followed by specifications of several subway lines. Each subway line consists of the non-negative integer x,y coordinates of each stop on the line, in order. You may assume the subway runs in a straight line between adjacent stops, and the coordinates represent an integral number of metres. Each line has at least two stops. The end of each subway line is followed by the dummy coordinate pair -1,-1. In total there are at most 200 subway stops in the city.
Output
Output is the number of minutes it will take you to get to school, rounded to the nearest minute, taking the fastest route.
Sample Input
0 0 10000 10000 200 5000 200 7000 200 -1 -1 2000 600 5000 600 10000 600 -1 -1
Sample Output
21
Source
Waterloo local 2001.09.22
代码为:
#include<cstdio>#include<iostream>#include<cstring>#include<algorithm>#include<queue>#include<cmath>#define INF 0x3f3f3f3fusing namespace std;const int maxn=200+10;double dis[maxn],gra[maxn][maxn];bool vis[maxn];int cal;struct Point{ int x,y;}point[maxn];queue<int>Q;double caldistance(Point a,Point b){ return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));}void Spfa(){ while(!Q.empty()) Q.pop(); for(int i=1;i<=cal;i++) { dis[i]=INF*1.0; vis[i]=false; } dis[1]=0; vis[1]=true; Q.push(1); while (!Q.empty()) { int temp=Q.front(); Q.pop(); vis[temp]=false; for(int i=1;i<=cal;i++) { if (dis[temp]+gra[temp][i]<dis[i]) { dis[i]=dis[temp]+gra[temp][i]; if(!vis[i]) { Q.push(i); vis[i]=true; } } } }}int main(){ int u,v; int last_point; double v1=40000.0/60; double v2=10000.0/60; while(~scanf("%d%d%d%d",&point[1].x,&point[1].y,&point[2].x,&point[2].y)) { cal=2,last_point=-1; memset(gra,0,sizeof(gra)); while(scanf("%d%d",&u,&v)==2) { if(u==-1&&v==-1) { last_point=-1; continue; } if(last_point==-1) { point[++cal].x=u, point[cal].y=v; last_point=cal; } else { point[++cal].x=u; point[cal].y=v; gra[last_point][cal]=gra[cal][last_point]=caldistance(point[last_point],point[cal])/v1; last_point=cal; } } for(int i=1;i<cal;i++) for(int j=i+1;j<=cal;j++) if(gra[i][j]==0) gra[i][j]=gra[j][i]=caldistance(point[i],point[j])/v2; Spfa(); printf("%d\n",int(dis[2]+0.5));//四舍五入 } return 0;}
0 0
- poj2502Subway(SPFA)
- poj3159(spfa+栈)
- HDU 2544 (SPFA)
- POJ 3256(SPFA)
- (spfa) XYZZY (P1932)
- hdu 1874 (spfa)
- 最短路(SPFA)
- poj2502(SPFA+建图)
- poj3159(spfa)
- uva10986Sending email (SPFA)
- poj1062(spfa)
- uva11090(二分spfa)
- uva11478(spfa求负环)
- spfa(还不懂--)
- 1452: 旅行(SPFA)
- Wormholes(SPFA)
- spfa(模板)
- POJ3259(SPFA算法)
- 2015-华为招聘公开测试题目-单词迷宫
- uva11081 - Strings(递推)
- 以后敲代码,第一行再也不要先写#include、import、using之类的了!
- 10-3. 字符串逆序(15)
- 10-4. 字符串循环左移(20)
- poj2502Subway(SPFA)
- 交叉编译glibc
- Java中final关键字作用及相关误区
- GDB基本命令(整合)
- 百度MP3地址使用(一)
- 黑马程序员_Java语言基础
- 【Nutch2.2.1源代码分析之4】Nutch加载配置文件的方法
- SPOJ 8282. Distance
- linux 调试利器gdb, strace, pstack, pstree, lsof