【乱搞/分治】【最短路】【线段树】Day 10.24

 1 #include <cstdio>
 2 #include <algorithm>
 3 #include <iostream>
 4 using namespace std;
 5 typedef pair<int,int> P;
 6 int n,a,b;
 7 P p[500001];
 8 double ans;
 9 void solve(int l,int r)
10 {
11     if (l>=r) return;
12     int mid=(l+r)/2;
13     for (int i=l;i<=r;i++) if (i!=mid)
14     {
15         ans=max(ans,double(p[mid].second-p[i].second)/(p[mid].first-p[i].first));
16     }
17     solve(l,mid-1);solve(mid+1,r);
18 }
19 int main()
20 {
21     freopen("slope.in","r",stdin);
22     freopen("slope.out","w",stdout); 
23     scanf("%d",&n);
24     for (int i=1;i<=n;i++)
25     {
26         scanf("%d%d",&a,&b);
27         p[i]=P(a,b);
28     }
29     sort(p+1,p+n+1);
30     ans=double(p[2].second-p[1].second)/(p[2].first-p[1].first); 
31     solve(1,n);
32     printf("%.3f",ans);
33 } 

 1 #include <cstdio>
 2 #include <iostream>
 3 #include <queue>
 4 #include <cstring>
 5 #define ll long long
 6 using namespace std;
 7 typedef pair<int,int> P;
 8 struct E{
 9     int next,to,w;
10 }e[250001];
11 priority_queue<P,vector<P>,greater<P> > que;
12 int n,m,a,b,c,sz=0,head[501],v[501],reg[501],f[501];
13 ll w[501][501];
14 void insert(int a,int b,int w)
15 {
16     sz++;
17     e[sz].next=head[a];
18     head[a]=sz;
19     e[sz].to=b;
20     e[sz].w=w;
21 }
22 void dijkstra(int s)
23 {
24     memset(reg,0,sizeof(reg));
25     memset(f,0x7f,sizeof(f));
26     f[s]=1;
27     que.push(P(0,s));
28     while(!que.empty())
29     {
30         int x=que.top().second;que.pop();
31         if (reg[x]) continue;
32         reg[x]=1;
33         for (int i=head[x];i;i=e[i].next)
34         {
35             if (v[e[i].to]<=v[s]&&f[e[i].to]>max(f[x],e[i].w))
36             {
37                 f[e[i].to]=max(f[x],e[i].w);
38                 que.push(P(f[e[i].to],e[i].to));
39             }
40         }
41     }
42     for (int i=1;i<=n;i++)
43         for (int j=1;j<=n;j++)
44             if (reg[i]&&reg[j]) w[i][j]=min(w[i][j],(ll)max(f[i],f[j])*v[s]);
45 }
46 int main()
47 {
48     freopen("path.in","r",stdin);
49     freopen("path.out","w",stdout);
50     ios::sync_with_stdio(false); 
51     memset(w,0x7f,sizeof(w));
52     cin>>n>>m;
53     for (int i=1;i<=n;i++) cin>>v[i];
54     for (int i=1;i<=m;i++)
55     {
56         cin>>a>>b>>c; 
57         insert(a,b,c);insert(b,a,c);
58     }
59     for (int i=1;i<=n;i++) dijkstra(i);
60     for (int i=1;i<=n;i++)
61     {
62         for (int j=1;j<=n;j++)
63         {
64             if (i==j){
65                 cout<<0<<" ";
66             }else{
67                 if (w[i][j]==w[0][0])
68                     cout<<-1<<" ";
69                 else
70                     cout<<w[i][j]<<" ";
71             }
72         }
73         cout<<endl;
74     }
75 }