Dijkstra算法的优化（堆+邻接表，优先队列+邻接表）hdu2544

Dijkstra算法的优化（堆+邻接表，优先队列+邻接表）hdu2544

Dijkstra算法的核心：选出一个已经求出最短路的点，加上一条边求出另一个点的最短路；d'[v]=min{d[u]+w(u,v)|u的最短距离已求出且边（u,v)存在}  借助堆取出d[u];
http://acm.hdu.edu.cn/showproblem.php?pid=2544
堆+邻接表
花了一上午。。。

#include < iostream >
using   namespace  std;
#define  N 110
#define  inf 0x7fffffff
typedef  struct  node {
    int adj;
    struct node * next;
    int w;
} node, * pnode;
node adjlist[N];
typedef  struct  Heap
{
    int x;
    int dis;
} Heap;
Heap heap[ 1000 ];
bool  hash[N];
int  len,d[N],n,m;
void  insert(Heap  in )
{
    int u=++len;
    while(u>1&&heap[u>>1].dis>in.dis)
    {
        heap[u]=heap[u>>1];
        u>>=1;
    }
    heap[u]=in;    
}
Heap pop()
{
    Heap first=heap[1],last=heap[len--];
    int u=1,v;
    while(2*u<=len)
    {
        v=u<<1;
        if(v+1<=len&&heap[v+1].dis<heap[v].dis)
            v++;
        if(heap[v].dis<last.dis)
            heap[u]=heap[v];
        else
            break;
        u=v;        
    }
    heap[u]=last;
    return first;
}
void  insert_adjlist( int  a, int  b,  int  c)
{
    pnode p,q;
    p=&adjlist[a];    
    while(p->next!=NULL)
        p=p->next;
    q=new node;
    q->adj=b;
    q->next=NULL;
    q->w=c;
    p->next=q;    
}
int  bfs()
{
    Heap min,in;
    pnode p;
    in.x=1;
    in.dis=0;
    d[1]=0;
    insert(in);    
    while(len)
    {
        min=pop();
        if(min.x==n)
            return min.dis;
        if(hash[min.x])
            continue;
        hash[min.x]=true;        
        p=adjlist[min.x].next;
        while(p!=NULL)
        {
            if(!hash[p->adj])
            {
                in.x=p->adj;
                in.dis=min.dis+p->w;
                if(in.dis<d[in.x])
                {
                    d[in.x]=in.dis;
                    insert(in);
                }
            }
            p=p->next;
        }
    }
    return -1;
}
int  main()
{
    int i,a,b,c,min;        
    while(scanf("%d%d",&n,&m),n+m)
    {
        for(i=1,len=0;i<=n;i++)
        {
            adjlist[i].next=NULL;
            hash[i]=false;
            d[i]=inf;
        }
        
        while(m--)
        {
            scanf("%d%d%d",&a,&b,&c);
            insert_adjlist(a,b,c);
            insert_adjlist(b,a,c);        
        }
        min=bfs();        
        printf("%d\n",min);
    }
}

优先队列+邻接表

#include < iostream >
#include < queue >
using   namespace  std;
#define  N 110
#define  inf 0x7fffffff
typedef  struct  node {
    int adj;
    struct node * next;
    int w;
} node, * pnode;
node adjlist[N];
typedef  struct  Heap
{
    bool operator <(Heap T)const
    {
        return T.dis<dis;
    }
    int x;
    int dis;
} Heap;
priority_queue < Heap > Q;
bool  hash[N];
int  len,d[N],n,m;
void  insert_adjlist( int  a, int  b,  int  c)
{
    pnode p,q;
    p=&adjlist[a];    
    while(p->next!=NULL)
        p=p->next;
    q=new node;
    q->adj=b;
    q->next=NULL;
    q->w=c;
    p->next=q;    
}
int  bfs()
{
    Heap min,in;
    pnode p;
    while(!Q.empty())
        Q.pop();
    in.x=1;
    in.dis=0;
    d[1]=0;
    Q.push(in);    
    while(!Q.empty())
    {
        min=Q.top();
        Q.pop();
        if(min.x==n)
            return min.dis;
        if(hash[min.x])
            continue;
        hash[min.x]=true;        
        p=adjlist[min.x].next;
        while(p!=NULL)
        {
            if(!hash[p->adj])
            {
                in.x=p->adj;
                in.dis=min.dis+p->w;
                if(in.dis<d[in.x])
                {
                    d[in.x]=in.dis;
                    Q.push(in);
                }
            }
            p=p->next;
        }
    }
    return -1;
}
int  main()
{
    int i,a,b,c,min;
    //freopen("123.out","w",stdout);
    while(scanf("%d%d",&n,&m),n+m)
    {
        for(i=1,len=0;i<=n;i++)
        {
            adjlist[i].next=NULL;
            hash[i]=false;
            d[i]=inf;
        }        
        while(m--)
        {
            scanf("%d%d%d",&a,&b,&c);
            insert_adjlist(a,b,c);
            insert_adjlist(b,a,c);        
        }
        min=bfs();        
        printf("%d\n",min);
    }
    return 0;
}

普通的Dijkstra

#include < stdio.h >
#define  min(a,b) a>b?b:a
#define  inf 0x7FFFFFFF
int  map[ 101 ][ 101 ];
int  minload[ 101 ];
int  visit[ 101 ];
int  main()
{
    int start,next,i,j,min,x,y,dis,n,m;
    while(scanf("%d%d",&n,&m),m||n)
    {
        for(i=1;i<=n;i++)
        {
            minload[i]=inf;
            visit[i]=0;
            for(j=1;j<=n;j++)
                map[i][j]=inf;
        }
        while(m--)
        {
            scanf("%d%d%d",&x,&y,&dis);
            map[x][y]=map[y][x]=dis;
        }
        start=1;
        visit[1]=1;
        minload[start]=0;
        while(start!=n)
        {
            min=inf;
            for(i=1;i<=n;i++)
            {
                if(map[start][i]!=inf)
                    minload[i]=min(minload[i],minload[start]+map[start][i]);
                if(!visit[i]&&minload[i]<min)
                {
                    next=i;
                    min=minload[i];
                }
            }            
            visit[next]=1;
            start=next;
        }
        printf("%d\n",minload[n]);
    }
}

折腾了半天，感觉如果是比赛的话还是选择最后一种模板，编程复杂度低点（假设题目条件不是那么苛刻 ）