UVA11374 Airport Express

Posted 2021-01-18 zytwan

走两次最短路然后枚举

  1 #include<bits/stdc++.h>
  2 using namespace std;
  3 const int maxn=10005;
  4 const int maxm=500005;
  5 const int INF=1000000000;
  6 
  7 inline int read()
  8 {
  9     int x=0,k=1;char c=getchar();
 10     while(c<‘0‘||c>‘9‘) {if(c==‘-‘) k=-1;c=getchar();}
 11     while(c>=‘0‘&&c<=‘9‘) x=(x<<3)+(x<<1)+(c^48),c=getchar();
 12     return x*k;
 13 }
 14 
 15 struct Edge{
 16     int u,v,w,next;
 17 }e[maxm];
 18 
 19 int head[maxn],cnt,n,m,k,vis[maxn],dis[maxn],d,a[maxn],b[maxn],pre[maxn],apre[maxn],bpre[maxn];
 20 
 21 struct node{
 22     int w,now;
 23     inline bool operator< (const node &x) const
 24     {
 25         return w>x.w;
 26     }
 27 };
 28 
 29 priority_queue<node>q;
 30 
 31 inline void add(int u,int v,int w)
 32 {
 33     e[++cnt].u=u;
 34     e[cnt].v=v;
 35     e[cnt].w=w;
 36     e[cnt].next=head[u];
 37     head[u]=cnt;
 38 }
 39 
 40 void dijikstra(int s)
 41 {
 42     for(int i=1;i<=n;++i) {dis[i]=INF;pre[i]=0;vis[i]=0;}
 43     dis[s]=0;
 44     q.push((node){0,s});
 45     while(!q.empty())
 46     {
 47         node x=q.top();
 48         q.pop();
 49         int u=x.now;
 50         if(vis[u]) continue;
 51         vis[u]=1;
 52         for(int i=head[u];i;i=e[i].next)
 53         {
 54             int v=e[i].v;
 55             if(dis[v]>dis[u]+e[i].w)
 56             {
 57                 dis[v]=dis[u]+e[i].w;
 58                 pre[v]=u;
 59                 q.push((node){dis[v],v});
 60             }
 61         }
 62     }
 63 }
 64 
 65 void init()
 66 {
 67     memset(head,0,sizeof(head));
 68     cnt=0;
 69 }
 70 
 71 void afs(int x)
 72 {
 73     if(apre[x])
 74     {
 75         afs(apre[x]);
 76         printf("%d ",x);
 77     }
 78     return;
 79 }
 80 
 81 void bfs(int x)
 82 {
 83     if(bpre[x])
 84     {
 85          printf("%d ",x);
 86          bfs(bpre[x]);
 87     }
 88     return;
 89 }
 90 
 91 int main()
 92 {
 93     int ans,Case=0;
 94     while(scanf("%d%d%d",&n,&m,&k)==3)
 95     {
 96         if(Case) printf("
");
 97         Case=1;
 98         d=read();
 99         for(int i=1,x,y,z;i<=d;++i)
100         {
101             x=read(),y=read(),z=read();
102             add(x,y,z);
103             add(y,x,z);
104         }
105         dijikstra(m);
106         for(int i=1;i<=n;++i) {a[i]=dis[i];apre[i]=pre[i];}
107         ans=a[k];
108         dijikstra(k);
109         for(int i=1;i<=n;++i) {b[i]=dis[i];bpre[i]=pre[i];}
110         init();
111         d=read();
112         int qi,shi,mid=0;
113         for(int i=1,x,y,z;i<=d;++i)
114         {
115             x=read(),y=read(),z=read();
116             if(a[x]+b[y]+z<ans)
117             {
118                 qi=x;shi=y;mid=x;
119                 ans=a[x]+b[y]+z;
120             } 
121             if(a[y]+b[x]+z<ans)
122             {
123                 qi=y;shi=x;mid=y;
124                 ans=a[y]+b[x]+z;
125             }
126         }
127         if(mid)
128         {
129         printf("%d ",m);
130         afs(qi);
131         bfs(shi);
132         printf("%d
",k);
133         printf("%d
%d
",mid,ans);
134         }
135         else
136         {
137         bfs(m);
138         printf("%d
",k);
139         printf("Ticket Not Used
%d
",ans);
140         }
141     }
142 }