POJ -- 2387 Til the Cows Come Home

来源：互联网发布：少女前线机枪数据编辑：程序博客网时间：2024/06/08 08:43

代码实现：

SPFA：

#include<stdio.h>#include<string.h>#include<queue>using namespace std;int dis[1010],visit[1010],cnt[1010],top,n,t;struct Edge{    int num,val;    Edge *next;    Edge(int n=0,int v=0,Edge *p=0):num(n),val(v),next(p){}}*h[1010],e[4010];void Addedge(int from,int to,int v){    Edge *p=&e[top++];    p->num=to;    p->val=v;    p->next=h[from];    h[from]=p;}queue<Edge>q;void SPFA(){    while(!q.empty()) q.pop();    for(int i=1;i<=n;i++) dis[i]=1e9;    dis[1]=0;    memset(visit,0,sizeof(visit));    memset(cnt,0,sizeof(cnt));    visit[1]=1;    Edge head(1,0);    Edge next;    q.push(head);    while(!q.empty()){        head=q.front();        q.pop();        visit[head.num]=0;        //printf("*%d %d\n",head.num,head.val);        for(Edge *p=h[head.num];p;p=p->next){            next=*p;            if(dis[next.num]>dis[head.num]+next.val){                dis[next.num]=dis[head.num]+next.val;                if(!visit[next.num]){                    cnt[next.num]++;                    if(cnt[next.num]>=n) return;                    visit[next.num]=1;                    q.push(next);                }            }        }    }}int main(){    while(~scanf("%d%d",&t,&n)){        top=0;        memset(h,0,sizeof(h));        int v1,v2,v;        while(t--){            scanf("%d%d%d",&v1,&v2,&v);            Addedge(v1,v2,v);            Addedge(v2,v1,v);        }        SPFA();        printf("%d\n",dis[n]);    }}

Dijkatra：

#include<stdio.h>#include<string.h>#include<queue>using namespace std;int dis[1010],visit[1010],cnt[1010],top,n,t;struct Edge{    int num,val;    Edge *next;    Edge(int n=0,int v=0,Edge *p=0):num(n),val(v),next(p){}    bool operator<(const Edge& a)const{        return val>a.val;    }}*h[1010],e[4010];void Addedge(int from,int to,int v){    Edge *p=&e[top++];    p->num=to;    p->val=v;    p->next=h[from];    h[from]=p;}void Dijkstra(){    priority_queue<Edge> q;    for(int i=1;i<=n;i++) dis[i]=1e9;    dis[1]=0;    memset(visit,0,sizeof(visit));    q.push(Edge(1,0));    while(!q.empty()){        int x=q.top().num;        q.pop();        if(visit[x]==1) continue;        visit[x]=1;        if(x==n) break;        for(Edge *p=h[x];p;p=p->next){            if(!visit[p->num]&&dis[p->num]>dis[x]+p->val){                dis[p->num]=dis[x]+p->val;                q.push(Edge(p->num,dis[p->num]));            }        }    }}int main(){    while(~scanf("%d%d",&t,&n)){        top=0;        memset(h,0,sizeof(h));        int v1,v2,v;        while(t--){            scanf("%d%d%d",&v1,&v2,&v);            Addedge(v1,v2,v);            Addedge(v2,v1,v);        }        Dijkstra();        printf("%d\n",dis[n]);    }}

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