POJ 2449 Remmarguts' Date K短路

K短路:dijkstra+A*(rec).

k短路问题模板.

#include<stdio.h>#include<string.h>#include<stdlib.h>#include<algorithm>#include<iostream>#include<queue>using namespace std;const int maxn=100010;int n,m,l;int dis[maxn];bool vis[maxn];int head1[maxn];int cnt[maxn];int head2[maxn];struct edge{     int to;     int next;     int val;}s1[maxn*2],s2[maxn*2];struct node{     int f;     int g;     int from;     bool operator < (node a)const     {          if(a.f==f)               return g>a.g;          return f>a.f;     }};void add(int x,int y,int k){     l++;     s1[l].to=y;     s1[l].next=head1[x];     s1[l].val=k;     head1[x]=l;     s2[l].to=x;     s2[l].next=head2[y];     s2[l].val=k;     head2[y]=l;}void spfa(int k){     int i,j;     for(i=1;i<=n;i++)          dis[i]=maxn;     dis[k]=0;     queue<int>q;     q.push(k);     vis[k]=1;     while(!q.empty())     {          int x=q.front();          q.pop();          vis[x]=0;          for(i=head2[x];i!=-1;i=s2[i].next)          {               int y=s2[i].to;               if(dis[y]>dis[x]+s2[i].val)               {                    dis[y]=dis[x]+s2[i].val;                    if(!vis[y])                    {                         q.push(y);                         vis[y]=1;                    }               }          }     }}int make(int x,int y,int k){     if(x==y)          k++;     if(dis[x]==maxn)          return -1;     priority_queue<node>q;     int sum=0;     node p1,p2;     p1.from=x;     p1.g=0;     p1.f=p1.g+dis[p1.from];     q.push(p1);     while(!q.empty())     {          p1=q.top();          q.pop();          if(p1.from==y)               sum++;          if(sum==k)               return p1.g;          for(int i=head1[p1.from];i!=-1;i=s1[i].next)          {               p2.from=s1[i].to;               p2.g=p1.g+s1[i].val;               p2.f=p2.g+dis[p2.from];               q.push(p2);          }     }     return -1;}int main(void){     int i,j,k;     int x,y,z;     while(scanf("%d%d",&n,&m)!=EOF)     {          for(i=1;i<=n;i++)          {               dis[i]=maxn;          }          l=0;          memset(head1,-1,sizeof(head1));          memset(head2,-1,sizeof(head2));          for(i=1;i<=m;i++)          {               scanf("%d%d%d",&x,&y,&k);               add(x,y,k);          }          scanf("%d%d%d",&x,&y,&k);          spfa(y);          z=make(x,y,k);          printf("%d\n",z);     }     return 0;}