题解：http://zyfzyf.is-programmer.com/posts/97953.html
按x坐标排序，相邻点之间连边。满足dist(x1,x3)<=dist(x1,x2)+dist(x2,x3)（因为可以走y）
再按y坐标排序，相邻点之间连边。同上
然而SPFA挂了……写了Dijkstra
1 /************************************************************** 2 Problem: 4152 3 User: Tunix 4 Language: C++ 5 Result: Accepted 6 Time:4304 ms 7 Memory:27204 kb 8 ****************************************************************/ 9 10 //BZOJ 4152 11 #include<vector> 12 #include<queue> 13 #include<cstdio> 14 #include<cstring> 15 #include<cstdlib> 16 #include<iostream> 17 #include<algorithm> 18 #define rep(i,n) for(int i=0;i<n;++i) 19 #define F(i,j,n) for(int i=j;i<=n;++i) 20 #define D(i,j,n) for(int i=j;i>=n;--i) 21 using namespace std; 22 typedef long long LL; 23 inline int getint(){ 24 int r=1,v=0; char ch=getchar(); 25 for(;!isdigit(ch);ch=getchar()) if (ch=='-') r=-1; 26 for(; isdigit(ch);ch=getchar()) v=v*10-'0'+ch; 27 return r*v; 28 } 29 const int N=2e5+10,INF=~0u>>1; 30 /*******************template********************/ 31 32 int head[N],to[N<<3],nxt[N<<3],l[N<<3],cnt; 33 void add(int x,int y,int z){ 34 to[++cnt]=y; nxt[cnt]=head[x]; head[x]=cnt; l[cnt]=z; 35 to[++cnt]=x; nxt[cnt]=head[y]; head[y]=cnt; l[cnt]=z; 36 } 37 int n,d[N]; 38 struct node{ 39 int x,y,num; 40 }a[N]; 41 bool cmpx(node a,node b){return a.x<b.x;} 42 bool cmpy(node a,node b){return a.y<b.y;} 43 typedef pair<int,int> pii; 44 #define mp make_pair 45 #define se second 46 priority_queue<pii,vector<pii>,greater<pii> >Q; 47 bool vis[N]; 48 int main(){ 49 #ifndef ONLINE_JUDGE 50 freopen("4152.in","r",stdin); 51 freopen("4152.out","w",stdout); 52 #endif 53 n=getint(); 54 F(i,1,n) a[i].x=getint(),a[i].y=getint(),a[i].num=i; 55 sort(a+1,a+n+1,cmpx); 56 F(i,1,n-1) add(a[i].num,a[i+1].num,a[i+1].x-a[i].x); 57 sort(a+1,a+n+1,cmpy); 58 F(i,1,n-1) add(a[i].num,a[i+1].num,a[i+1].y-a[i].y); 59 60 F(i,2,n) d[i]=INF; 61 d[1]=0; 62 Q.push(mp(0,1)); 63 while(!Q.empty()){ 64 int x=Q.top().se; Q.pop(); 65 if (vis[x]) continue; 66 vis[x]=1; 67 for(int i=head[x];i;i=nxt[i]) 68 if (d[to[i]]>d[x]+l[i]){ 69 d[to[i]]=d[x]+l[i]; 70 Q.push(mp(d[to[i]],to[i])); 71 } 72 } 73 printf("%d\n",d[n]); 74 return 0; 75 }