poj 2432 Around the world bfs+哈希
由于每个点的状态包含走过来的距离，所以要存二维的状态，但是状态总量太多，所以可以用哈希来搞。
那么就是bfs最短路，哈希记录状态了。
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int maxn=5e3+9;
int n,m;
int a[maxn];
struct
{
struct
{
int next,to;
}e[maxn*10];
int head[maxn],lon;
void clear()
{
memset(head,-1,sizeof(head));
lon=-1;
}
void add(int from,int to)
{
e[++lon].to=to;
e[lon].next=head[from];
head[from]=lon;
}
}edge;
struct
{
int head[111111],lon;
struct
{
int t,dist,next,sum;
}data[1111111];
void clear()
{
memset(head,-1,sizeof(head));
lon=-1;
}
bool push(int t,int dist,int sum)
{
int key=(t+abs(dist)%360*n)%111111;
for(int k=head[key];k!=-1;k=data[k].next)
{
if(t==data[k].t&&dist==data[k].dist)
return false;
}
data[++lon].t=t;
data[lon].dist=dist;
data[lon].next=head[key];
data[lon].sum=sum;
head[key]=lon;
return true;
}
}hash;
struct
{
int t,dist,sum;
}que[1111111];
int bfs()
{
hash.clear();
int front=1,end=0;
que[++end].t=1;
que[end].sum=que[end].dist=0;
hash.push(1,0,0);
while(front<=end)
{
int t=que[front].t;
int dist=que[front].dist;
int sum=que[front++].sum;
for(int k=edge.head[t];k!=-1;k=edge.e[k].next)
{
int u=edge.e[k].to;
int c=(a[u]+360-a[t])%360;
int uc=(a[t]+360-a[u])%360;
int tmp;
if(c<uc) tmp=c;
else tmp=-uc;
if(u==1&&dist+tmp!=0) return sum+1;
if(hash.push(u,dist+tmp,sum+1))
{
que[++end].t=u;
que[end].dist=dist+tmp;
que[end].sum=sum+1;
}
}
}
return -1;
}
int main()
{
// freopen("in.txt","r",stdin);
while(scanf("%d %d",&n,&m)!=EOF)
{
edge.clear();
for(int i=1;i<=n;i++)
scanf("%d",&a[i]);
for(int i=1,from,to;i<=m;i++)
{
scanf("%d %d",&from,&to);
edge.add(from,to);
edge.add(to,from);
}
cout<<bfs()<<endl;
}
return 0;
}
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int maxn=5e3+9;
int n,m;
int a[maxn];
struct
{
struct
{
int next,to;
}e[maxn*10];
int head[maxn],lon;
void clear()
{
memset(head,-1,sizeof(head));
lon=-1;
}
void add(int from,int to)
{
e[++lon].to=to;
e[lon].next=head[from];
head[from]=lon;
}
}edge;
struct
{
int head[111111],lon;
struct
{
int t,dist,next,sum;
}data[1111111];
void clear()
{
memset(head,-1,sizeof(head));
lon=-1;
}
bool push(int t,int dist,int sum)
{
int key=(t+abs(dist)%360*n)%111111;
for(int k=head[key];k!=-1;k=data[k].next)
{
if(t==data[k].t&&dist==data[k].dist)
return false;
}
data[++lon].t=t;
data[lon].dist=dist;
data[lon].next=head[key];
data[lon].sum=sum;
head[key]=lon;
return true;
}
}hash;
struct
{
int t,dist,sum;
}que[1111111];
int bfs()
{
hash.clear();
int front=1,end=0;
que[++end].t=1;
que[end].sum=que[end].dist=0;
hash.push(1,0,0);
while(front<=end)
{
int t=que[front].t;
int dist=que[front].dist;
int sum=que[front++].sum;
for(int k=edge.head[t];k!=-1;k=edge.e[k].next)
{
int u=edge.e[k].to;
int c=(a[u]+360-a[t])%360;
int uc=(a[t]+360-a[u])%360;
int tmp;
if(c<uc) tmp=c;
else tmp=-uc;
if(u==1&&dist+tmp!=0) return sum+1;
if(hash.push(u,dist+tmp,sum+1))
{
que[++end].t=u;
que[end].dist=dist+tmp;
que[end].sum=sum+1;
}
}
}
return -1;
}
int main()
{
// freopen("in.txt","r",stdin);
while(scanf("%d %d",&n,&m)!=EOF)
{
edge.clear();
for(int i=1;i<=n;i++)
scanf("%d",&a[i]);
for(int i=1,from,to;i<=m;i++)
{
scanf("%d %d",&from,&to);
edge.add(from,to);
edge.add(to,from);
}
cout<<bfs()<<endl;
}
return 0;
}
#include
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int maxn=5e3+9;
int n,m;
int a[maxn];
struct
{
struct
{
int next,to;
}e[maxn*10];
int head[maxn],lon;
void clear()
{
memset(head,-1,sizeof(head));
lon=-1;
}
void add(int from,int to)
{
e[++lon].to=to;
e[lon].next=head[from];
head[from]=lon;
}
}edge;
struct
{
int head[111111],lon;
struct
{
int t,dist,next,sum;
}data[1111111];
void clear()
{
memset(head,-1,sizeof(head));
lon=-1;
}
bool push(int t,int dist,int sum)
{
int key=(t+abs(dist)%360*n)%111111;
for(int k=head[key];k!=-1;k=data[k].next)
{
if(t==data[k].t&&dist==data[k].dist)
return false;
}
data[++lon].t=t;
data[lon].dist=dist;
data[lon].next=head[key];
data[lon].sum=sum;
head[key]=lon;
return true;
}
}hash;
struct
{
int t,dist,sum;
}que[1111111];
int bfs()
{
hash.clear();
int front=1,end=0;
que[++end].t=1;
que[end].sum=que[end].dist=0;
hash.push(1,0,0);
while(front<=end)
{
int t=que[front].t;
int dist=que[front].dist;
int sum=que[front++].sum;
for(int k=edge.head[t];k!=-1;k=edge.e[k].next)
{
int u=edge.e[k].to;
int c=(a[u]+360-a[t])%360;
int uc=(a[t]+360-a[u])%360;
int tmp;
if(c<uc) tmp=c;
else tmp=-uc;
if(u==1&&dist+tmp!=0) return sum+1;
if(hash.push(u,dist+tmp,sum+1))
{
que[++end].t=u;
que[end].dist=dist+tmp;
que[end].sum=sum+1;
}
}
}
return -1;
}
int main()
{
// freopen("in.txt","r",stdin);
while(scanf("%d %d",&n,&m)!=EOF)
{
edge.clear();
for(int i=1;i<=n;i++)
scanf("%d",&a[i]);
for(int i=1,from,to;i<=m;i++)
{
scanf("%d %d",&from,&to);
edge.add(from,to);
edge.add(to,from);
}
cout<<bfs()<<endl;
}
return 0;
}
<iostream>#include <cstdio>#include <cstring>using namespace std;const int maxn=5e3+9;int n,m;int a[maxn];struct{ struct { int next,to; }e[maxn*10]; int head[maxn],lon; void clear() { memset(head,-1,sizeof(head)); lon=-1; } void add(int from,int to) { e[++lon].to=to; e[lon].next=head[from]; head[from]=lon; }}edge;struct{ int head[1111111],lon; struct { int t,dist,next,sum; }data[1111111]; void clear() { memset(head,-1,sizeof(head)); lon=-1; } bool push(int t,int dist,int sum) { int key=t+abs(dist)%360*n; for(int k=head[key];k!=-1;k=data[k].next) { if(t==data[k].t&&dist==data[k].dist) return false; } data[++lon].t=t; data[lon].dist=dist; data[lon].next=head[key]; data[lon].sum=sum; head[key]=lon; return true; }}hash;struct{ int t,dist,sum;}que[1111111];int bfs(){ hash.clear(); int front=1,end=0; que[++end].t=1; que[end].sum=que[end].dist=0; hash.push(1,0,0); while(front<=end) { int t=que[front].t; int dist=que[front].dist; int sum=que[front++].sum; for(int k=edge.head[t];k!=-1;k=edge.e[k].next) { int u=edge.e[k].to; int c=(a[u]+360-a[t])%360; int uc=(a[t]+360-a[u])%360; int tmp; if(c<uc) tmp=c; else tmp=-uc; if(u==1&&dist+tmp!=0) return sum+1; if(hash.push(u,dist+tmp,sum+1)) { que[++end].t=u; que[end].dist=dist+tmp; que[end].sum=sum+1; } } } return -1;}int main(){// freopen("in.txt","r",stdin); while(scanf("%d %d",&n,&m)!=EOF) { edge.clear(); for(int i=1;i<=n;i++) scanf("%d",&a[i]); for(int i=1,from,to;i<=m;i++) { scanf("%d %d",&from,&to); edge.add(from,to); edge.add(to,from); } cout<<bfs()<<endl; } return 0;}
