HDU 1142 A Walk Through the Forest锛堟渶鐭矾+璁板繂鍖栨悳绱級
Posted
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了HDU 1142 A Walk Through the Forest锛堟渶鐭矾+璁板繂鍖栨悳绱級相关的知识,希望对你有一定的参考价值。
鏍囩锛?a href='http://www.mamicode.com/so/1/memset' title='memset'>memset
contest esc pos pat home tin 鍗曟簮鏈€鐭矾 iceA 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, 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 other. A nice walk through the forest, seeing the birds and chipmunks is quite enjoyable.
The forest is beautiful, and Jimmy wants to take a different route everyday. He also wants to get home before dark, so he always takes a path to make progress towards his house. He considers taking a path from A to B to be progress if there exists a route from B to his home that is shorter than any possible route from A. Calculate how many different routes through the forest Jimmy might take.
The forest is beautiful, and Jimmy wants to take a different route everyday. He also wants to get home before dark, so he always takes a path to make progress towards his house. He considers taking a path from A to B to be progress if there exists a route from B to his home that is shorter than any possible route from A. Calculate how many different routes through the forest Jimmy might take.
Input
Input contains several test cases followed by a line containing 0. Jimmy has numbered each intersection or joining of paths starting with 1. His office is numbered 1, and his house is numbered 2. The first line of each test case gives the number of intersections N, 1 < N ≤ 1000, and the number of paths M. The following M lines each contain a pair of intersections a b and an integer distance 1 ≤ d ≤ 1000000 indicating a path of length d between intersection a and a different intersection b. Jimmy may walk a path any direction he chooses. There is at most one path between any pair of intersections.
Output
For each test case, output a single integer indicating the number of different routes through the forest. You may assume that this number does not exceed 2147483647
Sample Input
5 6
1 3 2
1 4 2
3 4 3
1 5 12
4 2 34
5 2 24
7 8
1 3 1
1 4 1
3 7 1
7 4 1
7 5 1
6 7 1
5 2 1
6 2 1
0
Sample Output
2
4
Source
Recommend
棰樼洰鎰忔€濓細
杩欓亾棰樹笉鏄眰鏈€鐭矾鐨勬潯鏁帮紒锛侊紒
娉ㄦ剰浜?/span>
棰樼洰鏄濡傛灉A鍒扮粓鐐圭殑璺濈澶т簬B鍒扮粓鐐圭殑璺濈锛岄偅涔堟垜浠涓篈鍒癇鏄弧瓒虫潯浠剁殑璺緞
闂綘婊¤冻鏉′欢鐨勮矾鐨勬潯鏁?/span>
鍒嗘瀽锛?/span>
鍏堢敤缁堢偣鍋氳捣鐐圭劧鍚庢眰鍗曟簮鏈€鐭矾锛屽緱鍒版瘡涓偣鍒扮粓鐐圭殑璺濈
鐒跺悗閫氳繃璁板繂鍖栨悳绱紝鎼滄弧瓒虫潯浠剁殑璺緞鏁扮洰锛侊紒锛?/span>
涓昏鏄鐩剰鎬濋毦鎳傦紝寰堝鏄撹瑙f垚涓烘眰1鍒?鐨勬渶鐭矾鏉℃暟
code锛?/span>
#include<iostream> #include<stdio.h> #include<memory.h> using namespace std; #define max_v 1005 #define INF 9999999 int n,m; int vis[max_v]; int dis[max_v]; int e[max_v][max_v]; int dp[max_v]; void init() { memset(vis,0,sizeof(vis)); for(int i=0;i<=n;i++) { for(int j=0;j<=n;j++) { e[i][j]=INF; } dp[i]=-1; dis[i]=INF; } } void Dijkstra(int s) { for(int i=1;i<=n;i++) dis[i]=e[s][i]; dis[s]=0; for(int i=1;i<=n;i++) { int index,mindis=INF; for(int j=1;j<=n;j++) { if(!vis[j]&&dis[j]<mindis) { mindis=dis[j]; index=j; } } vis[index]=1; for(int j=1;j<=n;j++) if(dis[index]+e[index][j]<dis[j]) dis[j]=dis[index]+e[index][j]; } } int dfs(int v) { if(dp[v]!=-1) return dp[v]; if(v==2) return 1; int sum=0; for(int i=1;i<=n;i++) if(dis[v]>dis[i]&&e[v][i]!=INF) sum+=dfs(i); dp[v]=sum; return dp[v]; } int main() { while(~scanf("%d",&n)) { if(!n) break; scanf("%d",&m); init(); for(int i=0;i<m;i++) { int x,y,z; scanf("%d %d %d",&x,&y,&z); if(e[x][y]>z) e[x][y]=e[y][x]=z; } Dijkstra(2); printf("%d ",dfs(1)); } return 0; }
以上是关于HDU 1142 A Walk Through the Forest锛堟渶鐭矾+璁板繂鍖栨悳绱級的主要内容,如果未能解决你的问题,请参考以下文章
HDU1142 A Walk Through the Forest(最短路+DAG)
HDU 1142 A Walk Through the Forest(dijkstra+记忆化DFS)
HDU - 1142 A Walk Through the Forest(Dijkstra+DFS)
HDU 1142 A Walk Through the Forest