P2483 [SDOI2010]魔法猪学院
k短路模板
1 #include<queue> 2 #include<cstdio> 3 #include<cstring> 4 #include<algorithm> 5 using namespace std; 6 const int maxn=10005; 7 int n,m,s,t,k,num,head1[maxn*100],head2[maxn*100],tot; 8 int nxt1[maxn*100],nxt2[maxn*100],cnt; 9 double dis[maxn*100],e; 10 queue<int>q; bool vis[maxn]; 11 struct Edge{ 12 int u,v; 13 double d; 14 }edge1[maxn*100],edge2[maxn*100]; 15 16 struct Data{ 17 int num; 18 double h,g; 19 bool operator < (const Data x) const 20 { 21 if(h==x.h) return g>x.g; 22 return h>x.h; 23 } 24 }; 25 26 char ch; 27 inline void read(int &now) 28 { 29 ch=getchar(); now=0; 30 while(ch>'9'||ch<'0') ch=getchar(); 31 while(ch>='0'&&ch<='9') now=now*10+ch-'0',ch=getchar(); 32 } 33 34 void add_Edge(int u,int v,double d) 35 { 36 edge2[++num].u=u; 37 edge2[num].v=v; 38 edge2[num].d=d; 39 nxt2[num]=head2[u]; 40 edge1[num].u=v; 41 edge1[num].v=u; 42 edge1[num].d=d; 43 nxt1[num]=head1[v]; 44 head2[u]=num; 45 head1[v]=num; 46 } 47 48 void spfa() 49 { 50 for(int i=0;i<=n;i++) dis[i]=0x7f; 51 dis[t]=0; 52 vis[t]=1; 53 q.push(t); 54 while(!q.empty()) 55 { 56 int cur=q.front(); q.pop(); 57 for(int i=head2[cur];i;i=nxt2[i]) 58 { 59 int v=edge2[i].v; 60 if(dis[v]>dis[cur]+edge2[i].d) 61 { 62 dis[v]=dis[cur]+edge2[i].d; 63 if(!vis[v]) 64 { 65 vis[v]=1; 66 q.push(v); 67 } 68 } 69 } 70 vis[cur]=0; 71 } 72 } 73 74 int astar() 75 { 76 priority_queue<Data>que; 77 Data u,v,w; 78 u.num=s; 79 u.g=0; 80 u.h=dis[s]; 81 que.push(u); 82 while(!que.empty()) 83 { 84 v=que.top(); que.pop(); 85 if(v.num==t) 86 { 87 e-=v.g; 88 if(e>=0) tot++; 89 else return tot; 90 } 91 for(int i=head1[v.num];i;i=nxt1[i]) 92 { 93 w.num=edge1[i].v; 94 w.g=v.g+edge1[i].d; 95 w.h=w.g+dis[edge1[i].v]; 96 que.push(w); 97 } 98 } 99 } 100 101 int main() 102 { 103 read(n); read(m); scanf("%lf",&e); 104 for(int i=1;i<=m;i++) 105 { 106 int x,y; double z; 107 read(x); read(y); scanf("%lf",&z); 108 add_Edge(y,x,z); 109 } 110 s=1; t=n; 111 spfa(); 112 printf("%d ",astar()); 113 return 0; 114 }