hdu1142 深搜+dp+最短路径。

结合的好啊。。

  1 #include <cstdlib>

  2 #include <iostream>

  3 #include <queue>

  4 #include<vector>

  5 

  6 using namespace std;

  7 struct edge

  8 {

  9     int from,to,cost;

 10 };

 11 const int MAXN=1003;

 12 const int MAX=2147483647;

 13 bool in_queue[MAXN];//

 14 bool visited[MAXN];//

 15 int dist[MAXN];//

 16 //int sum=0;//

 17 int dp[MAXN];

 18 vector<edge>v[MAXN];//

 19 void spfa(int p)

 20 {

 21     int i=0;

 22     queue<int>q;

 23     while(!q.empty())

 24     {

 25         q.pop();

 26     }

 27     for(i=0;i<=MAXN-1;i++)

 28     {

 29         dist[i]=MAX;

 30     }

 31     dist[p]=0;

 32     q.push(p);

 33     in_queue[p]=1;

 34     while(!q.empty())

 35     {

 36         int i=0;

 37         int cur=q.front();

 38         q.pop();

 39         in_queue[cur]=0;

 40         for(i=0;i<=int(v[cur].size())-1;i++)

 41         {

 42             int cost=v[cur][i].cost+dist[cur];

 43             int to=v[cur][i].to;

 44             if(cost<dist[to])

 45             {

 46                 dist[to]=cost;

 47                 if(!in_queue[to])

 48                 {

 49                     q.push(to);

 50                     in_queue[to]=1;

 51                 }

 52             }

 53         }

 54     }

 55 }

 56 int dfs(int p)

 57 {

 58     int i=0;

 59     int sum=0;

 60     if(dp[p]!=-1)

 61     {

 62         return dp[p];

 63     }

 64     if(p==2)

 65     {

 66         return dp[p]=1;

 67     }

 68     for(i=0;i<=int(v[p].size())-1;i++)

 69     {

 70         int to=v[p][i].to;

 71         if((!visited[to])&&(dist[to]<dist[p]))

 72         {

 73             visited[to]=1;

 74             sum=sum+dfs(to);

 75             visited[to]=0;

 76         }

 77     }

 78     return dp[p]=sum;

 79 }

 80 int main(int argc, char *argv[])

 81 {

 82     int n,m;

 83     while((cin>>n)&&(n!=0)&&(cin>>m))

 84     {

 85         int dist2home[MAXN];

 86         int i=0;

 87         for(i=0;i<=MAXN-1;i++)

 88         {

 89             v[i].clear();

 90         }

 91 //        sum=0;

 92         memset(visited,0,sizeof(visited));

 93         memset(in_queue,0,sizeof(in_queue));

 94         memset(dp,-1,sizeof(dp));

 95         while(m--)

 96         {

 97             int from,to,cost;

 98             cin>>from>>to>>cost;

 99             edge e={from,to,cost};

100             v[e.from].push_back(e);

101             swap(e.from,e.to);

102             v[e.from].push_back(e);

103         }

104         spfa(2);

105         

106         cout<<dfs(1)<<endl;

107     }

108     //system("PAUSE");

109     return EXIT_SUCCESS;

110 }