bzoj4152 The Captain (dijkstra)

Posted 2021-01-09

鏍囩锛?a href='http://www.mamicode.com/so/1/c_1__1_' title='c++'>c++   struct   eof       push   col   node   gis   vector   

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 1 #include<bits/stdc++.h>
 2 #define pa pair<int,int>
 3 #define lowb(x) ((x)&(-(x)))
 4 #define REP(i,n0,n) for(i=n0;i<=n;i++)
 5 #define PER(i,n0,n) for(i=n;i>=n0;i--)
 6 #define MAX(a,b) ((a>b)?a:b)
 7 #define MIN(a,b) ((a<b)?a:b)
 8 #define CLR(a,x) memset(a,x,sizeof(a))
 9 #define rei register int
10 using namespace std;
11 typedef long long ll;
12 const int maxn=2e5+10;
13 
14 inline ll rd(){
15     ll x=0;char c=getchar();int neg=1;
16     while(c<鈥?/span>0鈥?/span>||c>鈥?/span>9鈥?/span>){if(c==鈥?/span>-鈥?/span>) neg=-1;c=getchar();}
17     while(c>=鈥?/span>0鈥?/span>&&c<=鈥?/span>9鈥?/span>) x=x*10+c-鈥?/span>0鈥?/span>,c=getchar();
18     return x*neg;
19 }
20 
21 struct Node{
22     int x,y,id;
23 }pos[maxn];
24 int N,xnxt[maxn][2],ynxt[maxn][2];
25 int dis[maxn],px[maxn],py[maxn];
26 bool flag[maxn];
27 priority_queue<pa,vector<pa>,greater<pa> > q;
28 
29 inline bool cmp1(Node a,Node b){return a.x<b.x;}
30 inline bool cmp2(Node a,Node b){return a.y<b.y;}
31 
32 inline void psh(int x,int d){
33     if(dis[x]==-1||d<dis[x]){
34         dis[x]=d;
35         if(!flag[x]) q.push(make_pair(d,x));
36     }
37 }
38 
39 inline void dijkstra(){
40     memset(dis,-1,sizeof(dis));dis[1]=0;
41     q.push(make_pair(0,1));
42     while(!q.empty()){
43         int p=q.top().second;q.pop();if(flag[p]) continue;
44         flag[p]=1;
45         if(p==N) return;
46         if(xnxt[p][0]) psh(xnxt[p][0],dis[p]+px[p]-px[xnxt[p][0]]);
47         if(xnxt[p][1]) psh(xnxt[p][1],dis[p]-px[p]+px[xnxt[p][1]]);
48         if(ynxt[p][0]) psh(ynxt[p][0],dis[p]+py[p]-py[ynxt[p][0]]);
49         if(ynxt[p][1]) psh(ynxt[p][1],dis[p]-py[p]+py[ynxt[p][1]]);
50     }
51 }
52 
53 int main(){
54     //freopen(".in","r",stdin);
55     rei i,j,k;
56     N=rd();
57     for(i=1;i<=N;i++) px[i]=pos[i].x=rd(),py[i]=pos[i].y=rd(),pos[i].id=i;
58     sort(pos+1,pos+N+1,cmp1);
59     for(i=1;i<=N;i++){
60         xnxt[pos[i].id][0]=pos[i-1].id;
61         xnxt[pos[i].id][1]=pos[i+1].id;
62     }
63     sort(pos+1,pos+N+1,cmp2);
64     for(i=1;i<=N;i++){
65         ynxt[pos[i].id][0]=pos[i-1].id;
66         ynxt[pos[i].id][1]=pos[i+1].id;
67     }
68     dijkstra();
69     printf("%d
",dis[N]);
70     return 0;
71 }